Xavier Niel

Technology entrepreneur Xavier Niel owns nearly 55% of publicly-traded Iliad, the parent company of his telecom outfit Free. Free Mobile, which Niel launched in 2012, sells unlimited calls, texts and Internet for far cheaper than its competitors in France. His portfolio includes ownership of Monaco Telecom and Orange Switzerland, the latter of which he acquired in 2014 for $2.9 billion and renamed Salt. Niel's initial venture, WorldNet, was France's first Internet provider. He started it in 1993 at age 25 and exited seven years later for $50 million.He financed the construction of a startup incubator, Station F, which opened in Paris in June, and created 42, a free computer programming school.