Michael Dell vs. Michael Bloomberg

Dell got his start at 19 selling computers out of his University of Texas dorm room, grossing $80,000 by the end of his freshman year. Dell's MSD Capital owns the Four Seasons Maui, plus indirect stakes in Applebees, IHOP, Calvin Klein and reportedly Grand Central Station.

In 2018, Bloomberg pledged $1.8 billion to Johns Hopkins University, his undergraduate alma mater, adding $1.5 billion he had already given the school. As a teenager, Bloomberg worked at an electronics company in Cambridge, Massachusetts.