The 25 richest self-made billionaires

Estimated net worth: $20.1 billion

Ka-Shing is one of the richest men in Asia, but his power far exceeds his wealth. He's known for investing in new, blossoming tech startups and was an early Facebook backer. Recently, the company he chairs, Hutchison Whampoa, bought the UK's second-largest mobile operator, O2. Last year he invested $23 million in plant-based egg-replacement company Hampton Creek through his firm Horizon Ventures.

Estimated net worth: $21 billion

The third-richest person in France, Drahi founded Altice, a multinational cable and telecommunications holding company, in 2002. Altice operates throughout France, Belgium, Israel, Portugal, and the Dominican Republic, and garnered international attention for its $1.8 billion IPO in January 2014. Drahi is coming to the US soon, too — he's taking over American cable company Suddenlink.

Estimated net worth: $21.6 billion

Knight and his old track coach each put up $500 to start the athletic shoe company now known as Nike. Today, more than 50 years later, the company is worth $86.2 billion. Knight remains as chairman.

Estimated net worth: $22.4 billion

Famous for his lively energy and numerous freak-outs, Ballmer served as CEO of Microsoft for 14 years before retiring in early 2014. He's still Microsoft's largest single shareholder, though. After leaving the tech world, Ballmer purchased the Los Angeles Clippers for a record-breaking $2 billion — the largest amount ever paid for an NBA team.

Estimated net worth: $22.8 billion

Even though he's almost 80, Icahn remains a powerful force in the finance world. He founded Icahn Enterprises, a diversified holdings company, in 1987 and invested in a myriad of industries, including tech and energy. He also owns a large stake in Apple, where his influence is certainly felt; a single tweet from the billionaire caused Apple stock to jump $8 billion in a day.

Estimated net worth: $23 billion

Del Vecchio founded Luxottica in 1961, and it's now the largest eyewear retailer in the world. Today Luxottica owns Sunglass Hut, Ray-Ban, and Oakley, and manufactures glasses for luxury brands like Burberry, Prada, and Versace. The Italian businessman still serves as chairman of the company, and recently showed his generous side by giving his Italian employees $10 million worth of shares in the company to celebrate his 80th birthday.

Estimated net worth: $24.8 billion

Touted as "the man who broke the bank of England," Soros is best known for the Quantum Fund, a hedge fund he launched in 1973 under his Soros Fund Management company. In 1992 he shorted the British pound, a risky move that ended up earning the fund $1 billion in a single day. Quantum Fund also generated annual returns over 30% under Soros' leadership, making it one of the most successful hedge funds of all time.

Estimated net worth: $26 billion

After selling COMDEX Trade Shows in 1995, Adelson used his profits to build up Las Vegas Sands, his casino operating company. Adelson remains chairman and CEO today, and despite setbacks, the casino industry has treated him well: He's the richest person in Nevada and one of the 20 richest in the world. Adelson's also known for his political contributions. In 2012, he gave $100 million to the Republican party.

Estimated net worth: $26.7 billion

Last year, Ma's e-commerce company Alibaba went public, garnering the largest IPO in history at $25 billion. Despite his humble beginnings as an English teacher, Ma became captivated by the internet during a visit to the US in 1995. He saw several business opportunities in it and eventually founded his e-commerce site in 1999.

Estimated net worth: $27 billion

The richest man in Brazil, Lemann founded and runs financial firm 3G Capital, which has stakes in Anheuser-Busch InBev, Burger King, and Tim Hortons. In March, 3G partnered with Warren Buffett's Berkshire Hathaway to invest in a merger between Heinz and Kraft, unifying the businesses into the fifth-largest food and beverage company in the world.

Estimated net worth: $28.3 billion

The grandson of first ruler of the Kingdom of Saudi Arabia Abdul Aziz al Saud, Prince Alwaleed is the richest man in Saudi Arabia. He founded investment firm Kingdom Holding Company in 1980, and invests in a number of large companies in both the Middle East and the US, including Twitter and Four Seasons Hotels, Inc.

Estimated net worth: $28.3 billion

Born in Guangdong, China, Lee Shau-kee moved to Hong Kong soon before Mao Zedong declared the foundation of the People's Republic of China. Lee cofounded a property company in 1963, and left in 1973 to found Henderson Land Development Company on his own. Today, he serves as chairman and managing director of the company and is also involved with Hong Kong and China Gas, Miramar Hotels, and other China-based companies.

Estimated net worth: $29.1 billion

Brin emigrated from Moscow to the US with his parents when he was a child. Before meeting his Google cofounder Larry Page at Stanford University, Brin earned a degree in mathematics and computer science from the University of Maryland. Today, he runs Google X, the semi-secret sector of Google dedicated to major technological innovation.

Estimated net worth: $31.3 billion

"BackRub" was the name of the 1996 project that Page and Sergey Brin built in their dorm rooms while they were doctoral candidates in computer science at Stanford University. For more than a year, the rudimentary search engine operated on the university's servers before it took up too much bandwidth. The pair left Stanford to start the company that became Google.

Estimated net worth: $33.7 billion

The richest person in New York, Bloomberg began his career at Salomon Brothers, where he joined as a trader and later became a partner. When the company was acquired, he used his severance to cofound Bloomberg L.P. in 1981. The company was designed to make market information accessible in real-time. Bloomberg served as the mayor of New York for three consecutive terms, and has been mentioned as a possible candidate for US presidency.

Estimated net worth: $35.2 billion

Wang Jianlin served in the army for 18 years before becoming involved in real estate. His great fortune makes him the richest man in China. After his time in the army, he joined Dalian Xigang Residential Development, which preceded Dalian Wanda, the state-owned property developer of which Wang is the chairman. In 2012, Dalian Wanda acquired AMC Entertainment, North America's second-largest movie theater chain.

Estimated net worth: $35.3 billion

Zuckerberg started Facebook during his sophomore year at Harvard University, after which he moved to California with his cofounders in order to nurture the company's growth. In 2006 he rejected an offer from Yahoo to acquire the company for $1 billion, which was a smart move considering that in 2012, Facebook's IPO raised $16 billion.

Estimated net worth: $35.4 billion

Slim studied engineering at the National Autonomous University (UNAM) in Mexico before going on to found companies that have interest in the financial, industrial, telecommunications, and media sectors, among others. Today, he controls more than 200 companies in Mexico and is one of the largest stockholders of The New York Times.

Estimated net worth: $39.8 billion

Bezos wrote Amazon's original business plan in the passenger seat while his wife drove the couple and their dog from the East Coast to Seattle, where he planned to found the company. After Amazon took off, Bezos founded the human spaceflight company Blue Origins in 2000. Bezos personally owns 18% of Amazon's shares, and the company is now disrupting the TV and film industry.

Estimated net worth: $48.1 billion

At 17, Kamprad founded Swedish furniture company IKEA with some money his father gave him as a reward for an academic achievement. IKEA is an acronym for Ingvar Kamprad Elmtaryd Agunnaryd, which combines his name, the name of his family's farm, and the nearest village. Kamprad currently serves as an informal senior advisor to the board of the IKEA Group, which is now an international furniture retailer.

Estimated net worth: $51.5 billion

Ellison went from programmer to entrepreneur in order to build his fame and fortune. He and two colleagues developed Oracle, a relational database management system used by the CIA. Ellison served as CEO until 2014 and is now the chairman and chief technology officer. He also has a massive real estate portfolio, which includes most of a Hawaiian island.

Estimated net worth: $65 billion

In 1975, the Spaniard cofounded Zara, a designer clothing store based on a reasonable price model. His company, Inditex, is the largest fashion group on earth. Ortega managed to avoid the financial crisis in Spain, growing his wealth by $45 billion from 2009 to 2014 with the growth of the company.

Estimated net worth: $70.1 billion

Buffett displayed financial prowess at a young age and purchased his first stock investment at 11 years old. By 13 he had his own small business delivering newspapers. Now chairman and CEO of Berkshire Hathaway, his company has the highest-priced stocks on the New York Stock Exchange, with Class A shares trading at over $200,000 each.

Estimated net worth: $85.7 billion

Gates started programming computers when he was only 13 years old. He founded Microsoft with childhood friend Paul Allen in 1975 after dropping out of Harvard. Along with many of his fellow billionaires, Gates has pledged to give away at least half of his wealth to charity after his death. In the mid-2000s, he transitioned most of his work towards the Bill and Melinda Gates Foundation, which supports numerous philanthropic causes worldwide.

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