Sheldon Adelson
Net worth: $26 billion

The son of a Boston cabdriver, he borrowed $200 from an uncle to sell newspapers at age 12. Later, he dropped out of college to become a court reporter. Now a casino and hotel magnate, Adelson took his Las Vegas Sands public in December 2004.

He worked at a young age selling newspapers on local street corners and owned his first business by the time he was twelve. In the years that followed, he worked as a mortgage broker, investment adviser and financial consultant. He started a business selling toiletry kits, and in the 1960s he started a charter tours business with two friends. He went to college at City College of New York but did not complete a degree there.

The basis for Adelson’s wealth and current investments was the computer trade show COMDEX, which he and his partners developed for the computer industry; the first show was in 1979. It was the premier computer trade show through much of the 1980s and 1990s.

In 1988, Adelson and his partners purchased the Sands Hotel & Casino in Las Vegas, Nevada, the former hangout of Frank Sinatra and the Rat Pack, in order to bring Las Vegas to a new phase of business centricity through the exhibition industry.