Stephen Bisciotti

Steve Bisciotti worked in staffing for a year after college before starting Allegis Group in 1983 with his cousin, fellow billionaire Jim Davis.

What started in a basement has evolved into the largest staffing firm in the U.S., with more than $14 billion in annual revenue.

Bisciotti also owns the NFL's Baltimore Ravens, worth $5.8 billion (net of debt). The team most recently won a Super Bowl title in 2013.

Bisciotti, who was raised by a single mother in Baltimore, studied liberal arts at nearby Salisbury State University.

Growing up, Bisciotti played football, basketball, and baseball; today he also enjoys golfing and boating.