Musk has also always been a tech nerd at heart. He was immediately captivated by the first computer he encountered at age 10 and was relentless in pushing his father to buy him one. When he got the computer, Musk learned how to use the computer in three days without sleeping. "It seemed like the most super-compelling thing I had ever seen," says Musk.
At 16, Musk and his younger brother Kimbal wanted to become entrepreneurs: They tried to open a video arcade near their school. "We had a lease, we had suppliers, but we were actually stopped," Kimbal says in a 2012 profile of Elon Musk in Esquire. "We got stopped by the city. We couldn't get a variance (a real estate permit). Our parents had no idea. They flipped out when they found out, especially my father."
Late CEO of Apple
Net worth at time of death: $7 billion in Sept. 2011, according to Forbes
Steve Jobs did not set out with a clear objective in life. To the contrary. He did a lot of wondering. But he also always pushed boundaries and was entrepreneurial from early on.
He grew up in Mountain View, Calif., the center of what would become Silicon Valley. In high school, he smoked pot, dropped LSD and experimented with how his brain would feel when deprived of sleep.
At 17, he and pal (and future co-founder Steve Wozniak) had their first entrepreneurial venture — they built and sold "blue boxes," illegal devices that allowed people to make free long distance phone calls, for about $170 a pop, according to Slate.