There are two types of billionaires: those who inherited their wealth, and those who built it from nothing.
Our friends at Wealth-X, a firm that does research and net worth valuations on ultra-high net worth individuals, focused on the latter to compile a list of the wealthiest self-made billionaires in the world.
From tech mogul Bill Gates to Alibaba founder Jack Ma, here's who made the list.
25. Len Blavatnik

Estimated net worth: $20.1 billion
Though he's known as one of Britain's richest residents, Blavatnik is a native of Ukraine. He earned degrees at Moscow State University, Columbia, and Harvard Business School before founding Access Industries in 1986 and investing in aluminum and chemical companies. In recent years he began investing in tech, with stakes in Spotify and Beats. Blavatnik also owns Warner Music, which he bought in 2011 for $3.3 billion.
Source: Wealth-X
24. Li Ka-Shing

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.
Source: Wealth-X
23. Patrick Drahi

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.
Source: Wealth-X
See the rest of the story at Business Insider