Michael Dell
Net Worth: $16.4 billion
Dropped out of University of Texas, Austin
Soft-spoken Texan reclaimed chief executive spot at Dell Computer in January 2007 for first time since 2004 after numerous setbacks pummeled company’s shares. Lost No. 1 spot in PC market to Hewlett-Packard in 2006 as company’s long-standing practice of shunning retail outlets and selling desktop PCs directly to customers over the phone or Internet floundered. Started selling computers from U. of Texas dorm room 1984 with $1,000; dropped out to start Dell. Took public 1988, grew fast with direct-sales model. Most of net worth now outside Dell.

Paul Allen
Net Worth: $16 billion
Dropped out of Washington State University
Microsoft cofounder may be one of most hopeful tech investors ever. Spent eight years at company he started in 1975 with Bill Gates–and 24 years after quitting, it still provides a quarter of his net worth. Lost huge sums on far-off visions, including Interval Research Group (tiny solar-powered, wearable computers; shuttered in 2000). Still has fun: rock ‘n’ roll museum in Seattle, basketball’s Portland Trail Blazers, football’s Seattle Seahawks, 413-foot yacht. Attended prestigious Lakeside School with Gates in Seattle. Dropped out of Washington State.

Jack Taylor
Net Worth: $14 billion (with family)
Dropped out of Washington University
Left Washington U. to serve in Navy; became fighter pilot on U.S.S. Enterprise during World War II. Sold cars after war, became sales manager for St. Louis Cadillac distributor. Backed by boss, took 50% pay cut to start own car-leasing business; offered rentals as temporary replacements for stolen, wrecked cars. Business boomed in 1970s after courts made insurance companies pay for replacement rentals. Today, Enterprise Rent-A-Car sales exceed $9 billion. Son Andrew began working for dad "as soon as I could drive"; now chairman and chief executive. Daughter, Jo Ann Taylor Kindle, is president of charitable Enterprise Rent-A-Car Foundation.