Billionaire Richard Branson dropped out of high school at the age of 15 to start a magazine with the $3,000-$4,000 he had raised. "I quit school...with the headmaster saying, 'You're either going to prison or you're going to become a millionaire'," Branson recalled during a podcast. Branson, who later founded the Virgin Group, has a net worth of $3.7 billion.