Michael Dell — Dell Technologies

Michael Dell dropped out of UT Austin at 19 after his dorm-room PC business earned $80,000 a month—and turned it into Dell Technologies, now worth over $100 billion. He took the company private in 2013 for $24.9 billion, the largest tech buyout at the time, then took it public again, boosting his net worth to $120 billion. Dell's resilient pivot from hardware to enterprise IT remains a blueprint for dorm-room entrepreneurs.