388. David Zalik
$2 billion Self-made Score: * Source: technology age: 43 residence: atlanta dropout, auburn The son of a math professor, Zalik frequently picked up the thick applied mathematics textbooks lying around the house as a kid. After scoring over 1500 on his SATS as a middle-schooler, he skipped high school and enrolled at Auburn. He dropped out before getting his degree to focus on a computer-assembly business. The math whiz went on to start Greensky, which facilitates home improvement loans via a network of contractors. The company, of which he owns about half, is valued at $3.6 billion.