A proliferation of IPOs created several new billionaires in 2019 ' but a turbulent stock market also knocked many entrepreneurs out of the three-comma club.Several one-time billionaires (includingJuul cofounders Adam Bowen and James Monsees) saw their net worths drop because of company crises.A few noteworthy newly-minted millionaires this year hail from the entertainment industry, including Kylie Jenner and Jay-Z.Visit Business Insider's homepage for more stories.Not everyone who becomes a billionaire stays one.A proliferation of IPOs created several new billionaires in 2019 ' but a turbulent stock market also knocked many entrepreneurs out of the three comma club.Last year was not an easy year to be a billionaire, Business Insider previously reported. 2018 was the first time in seven years that high net worth individuals saw their fortunes shrink, according to French technology consulting firm Capgemini. Billionaires across the globe lost 7% of their collective net worth in 2018 due to market instability at the end of the year,Wealth-X also found in its 2019 Billionaire Census. Slowing economic growth across the globe and trade tensions also contributed to the wealth drop, according to Wealth-X.Keep reading to learn more about the people who became billionaires ' and those who lost their billionaire status ' in 2019.SEE ALSO:Bill Gates isn't interested in space exploration and doesn't like Elizabeth Warren's wealth tax: Here are 5 highlights from the billionaire's DealBook interviewDON'T MISS:7 nannies who work for the rich and powerful share the worst things they've ever been asked to do on the jobSocial media and makeup mogul Kylie Jenner made headlines when she was declared "the world's youngest self-made billionaire" by Forbes in March.Net worth: $1 billion as of March 2019Jenner, who turned 22 in August, has built up a cosmetics empire, starred alongside her family in "Keeping Up with the Kardashians" as well as in her own spin-off show "Life of Kylie," started a clothing line with her sister, andmade millions promoting products on Instagram.Forbes estimated that Jenner's company, Kylie Cosmetics, is worth $900 million. That plus the cash she has pulled in from the business brings her to billionaire status, Forbes said.Many have criticized Forbes calling Jenner "self-made," saying she was born into wealth and privilege, as Business Insider's Katie Warren previously reported. In February,Jenner responded to the backlash in an interview with Paper magazine, saying, "The self-made thing is true" and adding that her parents "cut her off at the age of 15."Proactiv founders Katie Ronan and Kathy Fields were also declared billionaires by Forbes in March.Net worths: $1.5 billion each as of March 2019Ronan and Fields, 64 and 61 respectively, met when they were young dermatology residents, fresh out of medical school, according to their website. They may be best known for inventing acne treatment line Proactiv, but it's their multi-level marketing skincare line Ronan + Fields that made the duo of dermatologists ultrawealthyRodan + Fields' 300,000 independent consultants have sold $1.5 billion of cosmetics in 2017, Forbes reported in March.Zoom's stock soared in the video-conferencing company's public trading debut in April, making CEO Eric Yuan a billionaire.Net worth: $3 billion as of April 2019Before he founded Zoom in 2011, Yuan was the vice president of engineering at Cisco. He first came to the US fom China in 1997 after unsuccessfully applying for a visa eight times, Yuan said in a 2017 interview with Thrive Global. On his ninth try, Yuan was accepted, and he came to the country without speaking any English, CNBC reports. Yuan, Zoom's founder and CEO, owns 20.5% of his company's stock.Jay-Z became "hip-hop's first billionaire" in June, according to Forbes.Net worth: $1 billion as of June 2019The rapper has earned millions from sellout tours and chart-topping albums over the course of his nearly 30-year career, Business Insider's Mark Abadi previously reported. But music is far from his only money-making venture.Over the years, Jay-Z has parlayed his success in the hip-hop world into a fortune earned as an entrepreneur. His business ventures include entertainment labels, a clothing line, upscale alcohol brands, and the music-streaming service Tidal.Slack founder and CEO Stewart Butterfield was also declared a billionaire in June, after the workplace messaging app's direct listing.Net worth: $1.6 billion as of June 2019Slack's market debut may have been what made Butterfield, 46, a billionaire, but it wasn't the first successful company he founded, Business Insider's Megan HernbrothandRebecca Aydin previously reported. Butterfield also founded photo-sharing site Flickr, which he sold to Yahoo for more than $20 million in 2013.Both Slack and Flickr grew out of failed attempts to create an online video game.The launch of a new tech-focused stock market in China minted three billionaires in a single day in July.Net worths: Between $1.3 billion and $2.4 billion as of July 2o19Launched on July 22, the STAR market was designed to compete with Nasdaq to trade China's largest tech companies,Business Insider previously reported. By the end of the first day of trading, the market's 25 stocks were up an average of 140%, according to CNN Business. The highest performer, semi-conductor part makerAnji Microelectronics Technology, closed up 400%.Three new Chinese billionaires were minted on July 22:The founder of circuit makerSuzhou HYC TechnologyChen Wenyuan was the biggest beneficiary of the market's success, according toBloomberg.Bloombergestimates Wenyuan's net worth to be $2.4 billion.Cao Ji, the chairman of lithium battery producer Zhejiang Hangke Technology, now has a net worth of $2.2 billion, according toBloomberg.The founder and chairman of Arcsoft Corp, Hui Deng, is worth $1.3 billion, according toBloomberg.SmileDirectClub founders Jordan Katzman and Alex Fenkell became two of the youngest billionaires in the US in September after the company's IPO.Katzman's net worth: $1.2 billion as of September 2019Fenkell's net worth: $1 billion as of September 2019Shares of Katzman's and Fenkell's direct-to-consumer dental-product company SmileDirectClub closed down 28%after its first day of trading, but its market cap of $6.4 billion made Katzman and Fenkelleach of whom owns close to a quarter of the company's class B sharesbillionaires.The two,who both wore metal braces, became close friends. They came up with the idea for SmileDirectClub while reminiscing about their childhood years and wondering whether they could find a less embarrassing and cheaper way to straighten teeth,according to SmileDirectClub's website.A 24-year-old Wharton graduate who has posted photos of himself partying with Rihanna and Bella Hadid became a billionaire on October 23, thanks to a generous "gift" from his parents.Net worth: $3.8 billion as of October 2019Eric Tse now owns 2.7 billion shares, or 21.45%, of Sino Biopharmaceutical, the companyfounded by his father, the company said in a statement October 23.The company said Tse's parents told the board they transferred the shares to Tse to "refine the management and inheritance of family wealth" and planned for Tse to "hold the relevant shares in long-term." But Sino Biopharmaceutical said Tse's new status would "not have any material impact on the business operations of the Company."Despite having famous friends, Tse has said he doesn't want to be recognized for his wealth.Tse "indicated that in response to nomination for Billionaire List or wealth ranking organized by media or other organizations, he will endeavor not to participate in such rankings in his own name, and would recommend participating in such nominations in the name of the Tse Ping family," Sino Biopharmaceutical said.Oracle co-CEO Safra Catz is one of only a few people to become a billionaire from a company she did not found.Net worth: $1.1 billion as of November 2019Catz, 57, took over as co-CEO of software developer Oracle after the retirement of fellow billionaire Larry Ellison in 2014, according to Forbes. Catz is now one of the highest-paid women in the world, making $135 million in 2017, Forbes reported.Early Uber employee Ryan Graves was added to Forbes' Billionaires List this year.Net worth: $1.6 billion as of March 2019Graves, 35, was the first employee hired by former Uber CEO Travis Kalanick after responding to a January 2010 tweet from Kalanick asking where Kalanick could find an "entrepreneurial product mgr/biz-dev killer 4 a location based service," CNBC reported in May.Tweet Embed: //twitter.com/mims/statuses/7422940444'ref_src=twsrc%5Etfw @KonaTbone heres a tip. email me :) graves.ryan[at]gmail.comCanada Goose CEO Dani Reiss became a billionaire in March, when Forbes estimated his net worth to be $1.3 billion.Net worth: $1.3 billion as of March 2019Reiss, 46, took over the luxury outerwear company founded by his grandfather in 2001, according to Forbes. He made his Forbes Billionaires List debut in 2019, two years after taking the celeb-adored retailer public.Juul cofounders Adam Bowen and James Monsees had short-lived tenures as billionaires.Net worths: $900 million eachOne of the company's biggest investors, hedge fund Darsana Capital Partners, reportedlycut the company's valuation by more than a third on October 3 following increased attention from regulators. As a result, Juul cofounders Adam Bowen and James Monsees lost their billionaire status just ten months after attaining it, Business Insider previously reported.Bowen and Monsees founded Juul after meeting on smoke breaks while studying product design at Stanford University in 2004,Business Insiderpreviously reported. Ploom, a precursor to Juul, was launched in 2007 and first released Juul products in 2015. The company's Juul line was spun into a separate firm in 2017. The majority of the pair's respective net worths are tied to their 1.75% stakes in the e-cigarette maker,Forbes' Sergei Klebnikov reported.Forever 21's cofounders lost their billionaire status in July ' just three months before the fast-fashion retailer filed for bankruptcy in September.Net worths: $800 million eachAt the company's peak in 2015, Jin Sook and Do Won Chang had a combined net worth of $5.9 billion, Business Insider previously reported. Their combined fortune has fallen to $1.6 billion as the fast fashion chain enters bankruptcy proceedings. Forever 21 will close 350 stores across the globe, but will continue to operate in select locations and online.The married couple founded Forever 21 in Los Angeles in 1984 after emigrating from South Korea three years prior. Their first location, originally called Fashion 21, was 900 square feet and stocked merchandise the Changs purchased at wholesale close-out sales, according toForbes.WeWork founder Adam Neumann's net worth plummeted $3.5 billion in just seven months.Net worth: $600 million as of October 2019The former WeWork CEO's net worth parallels the plunging valuation of his coworking empire following the company's up-and-down IPO adventure that saw it whipsaw from a $47 billion valuation to talk of bankruptcy in just six weeks.The drop in Neumann's personal net worth from a peak of $4.1 billion was the result of the declining value of Neumann's 18% stake in WeWork, Forbesreported. WeWork wasvalued at $47 billion in Januaryfollowing an investment from Japanese investment firm Softbank. However, the company reportedly sought a valuation as low as $10 billion in September as public scrutiny over its steep losses and leadership structure threatened its IPO.Forbesnow estimates that the company is worth "at most $2.8 billion."But Neumann may have regained his billionaire status thanks to Softbank's bailout of WeWork, though estimates of his exact net worth vary. The former CEO is worth "at least one billion," according to Bloomberg. As of November 11, Forbes also puts Neumann's real-time net worth at $1 billion.WeWork cofounder Miguel McKelvey also lost his membership in the three comma club between March and October.Net worth: $400 million as of November 2019McKelvey founded WeWork in 2010 alongside Neumann and Neumann's now-wife Rebekah Neumann, Business Insider previously reported. Concern from potential investors over the company's finances and corporate governance issues pushed Neumann to resignas WeWork's CEO on September 24.Forbes estimated McKelvey to be worth $2.9 billion in March.RyanAir's falling stock price knocked CEO Michael O'Leary off Forbes' Billionaires List in March.Net worth: $1.1 billion in 2018O'Leary, 58, has served as the CEO of the cut-rate airline since 1994, according to Forbes. O'Leary once compared RyanAir's business model to that of Wal-Mart, according to Forbes, saying the airline aims to "pile it high and sell it cheap."The airline struggled with falling profits, Brexit concerns, the Boeing 737 Max grounding, and pilot strikes throughout 2018, sinking the company's shares. RyanAir's declining stock price brought O'Leary's net worth below $1 billion, The Independent's Samantha McCaughren reported in January, though his current net worth is unknown.Four heirs to the Barilla pasta fortune also dropped off Forbes' Billionaires List in March.Net worth: $1.1 billion each in 2018Siblings Emanuella, Guido, Luca, and Paolo Barilla share an 85% stake in the largest company in the world, Forbes reported in 2016. At the time, Forbes estimated that the siblings were worth about $1.5 billion each.Guido Barilla serves as the Barilla's chairman, while Luca Barilla and Paolo Barilla are both vice-chairmen.Isaac Larian, the CEO of Little Tikes and Bratz dolls maker MGA Entertainment, was also kicked off of Forbes' list.Net worth: $1.1 billion in 2018Larian, 65, immigrated to the United States from Iran in 1971 before founding MGA Entertainment in 1979 after seeing a talking doll that Mattel rejected, according to Forbes.An heiress to Krispy Kreme-owner JAB Holdings may no longer be a billionaire, but she's still the richest person in New Hampshire, according to Forbes.Net worth: $720 million as of June 2019Andrea Reimann-Ciardelli, 62, relocated from Germany to Hanover, New Hampshire, Forbes reported. Reimann-Ciardelli inherited a stake in her family's investment firm JAB Holdings, which she sold to relatives in 2003, according to Forbes. JAB also owns Peet's Coffee and Panera Bread.Money manager Charles Brandes fell off Forbes' Billionaires list in March.Net worth: $1.2 billion in 2018Brandes, 76, built his fortune running Brandes Investment Partners, the San Diego-based investment management firm he founded in 1974. according to Forbes. At its peak, Brandes had over $100 billion under management, but now has only $31 billion, Forbes reported. Brandes left the firm in February 2018. Click here to read full news..