Schooling: High school diploma and some college
Money made: Trade shows and casinos
Best-known venture: Las Vegas Sands
Sheldon Adelson grew up the son of a cab driver in Boston's rough Dorchester neighborhood. He started selling newspapers at the age of 12 and later dropped out of college to become a court reporter. According to The New York Times, Adelson sold toiletry kits to motels and tried mortgage brokering, then struck it rich when he founded Comdex, an annual computer trade show. He went on to build Las Vegas hotels around conventions, rather than casinos—not that he left the casinos out. At the end of 2006, The Times has estimated, Adelson's net worth had grown by about $1 million an hour for two straight years.