Steve Ballmer (net worth: $25.2 billion)

Born in 1956 in Detroit, Michigan, Steve Ballmer is the former CEO of Microsoft, the world’s biggest software maker. He stepped down in February 2014 and remains the largest individual shareholder of the company, which makes the Windows operating system, the Xbox360 game console, and Surface tablet computers. The billionaire bought the NBA team LA Clippers in 2014.