Wealth X, a research company, specialized in analysing and calculating the property of the most wealthy people on the planet, found those who didn't inherit their fortune, but they built it from scratch.
Fortune: $85,7 billion
He started taking programming lessons at the age of 13. He co-founded Microsoft when he was 20, after he abandoned college, and he held the positions of chairman, CEO and chief software architect, and was the largest individual shareholder until May 2014. He's included in the list of the world's wealthiest people. He has promised to bequeath most of his wealth to charity.
Fortune: $70,1 billion
At 11, he bought three shares of Cities Service Preferred for himself, and three for his sister Doris Buffett, while at 15 he made over $175 monthly delivering Washington Post newspapers. Today he is the chairman, CEO and largest shareholder of Berkshire Hathaway, and consistently ranked among the world's wealthiest people. He's also the founder of Giving Pledge, a campaign to encourage the wealthiest people in the world to make a commitment to give most of their wealth to philanthropic causes.
Fortune: $65 billion
In 1975, he opened his first Zara store in order to sell designer clothes in normal prices. Today, Zara is part of the Inditex group, of which Ortega owns 59.29%, increase his fortune by $45 billions for the last six years.
Fortune: $51,5 billion
The 70-year-old founder of Oracle began as a programmer and became wealthy by dominating the mainframe relational database market. He was the chief executive officer of the software company Oracle Corporation between its foundation in 1977 and 2014. In 2014, he was listed by Forbes as the third-wealthiest man in America and as the fifth-wealthiest person in the world.
Fortune: $48,1 billion
He founded IKEA when he was 17. Today he is one of the richest people in the world. IKEA is the world's largest furniture retailer.
Fortune: $39,8 billion
He founded Amazon in 1994, when he was 30, after he wrote the business plan while driving to Seattle. Amazon is the world's largest online retailer. Since 2000, Bezos has founded Blue Origin, a human spaceflight startup company.
CARLOS SLIM HELÚ
Fortune: $35,4 billion
His first investment began at the age of 11, when he invested in a government savings bond that taught him about the concept of compound interest. Known as the "Warren Buffett of Mexico," Slim oversees a vast business empire that is influential in every sector of the Mexican economy and accounts for 40% of the listings on the Mexican Stock Exchange.
Fortune: $35,3 billion
His story is well known. He founded Facebook in 2004 and, after he moved to California in 2006, he rejected Yahoo's offer to buy Facebook for 1 billion dollars. Today his company is worth $202 billion and it's the 22nd world largest company.
Fortune: $35,2 billion
A former military who became a businessman and one of the most wealthy men in China. He serves as the Chairman of the Dalian Wanda Group, China's largest real estate developer, as well as the world's largest movie theater operator.
Fortune: $33,7 billion
He began his career as an analyst and a trader in Salomon Brothers, before forming Bloomberg L.P. in 1981 and spending the next twenty years as its chairman and CEO.
Fortune: $31,3 billion
In 1996, he and Sergey Brin founded the company that later became known as Google.
Fortune: $29,1 billion
He and his parents left Russia to migrate to the USA when he was a kid. He and Larry Page met and founded Google.
Fortune: $28,3 billion
In 1963, at his 35, he participated in Hong Kong in a real estate company. In 1973 he founded his own company, Henderson Land Development Company, with interests in properties, hotels, restaurants and internet services.
JORGE PAULO LEMANN
Fortune: $27 billion
Brazil's richest man has also built his fortune from scratch. He is the founder of 3G Capital since 2004. In September 2010, 3G launched a $4 billion bid, at a 45% premium over market, for all the stock of Burger King. He is ranked as the 26th richest person in the world by Bloomberg Billionaire Index, with an estimated net worth of US$25 billion as of February 2015.