He is running two world changing companies: Electric car maker Tesla, and private space exploration company SpaceX. He's also chairman of SolarCity, a company that does solar panels for homes.

Musk splits his time between his two companies. He's at SpaceX's LA-based headquarters on Monday and Thursday, then he heads to Tesla (in the Bay Area) on Tuesday and Wednesday. On Friday he splits time between both. Tesla Design has offices in the same office park as SpaceX.

If you're unfamiliar with Musk, he became wealthy when eBay bought PayPal for $1.5 billion. Unlike other PayPal executives who got rich from that deal, he veered away from web-based companies.

He poured the money he made from the acquisition into his own companies. Four years ago, Tesla was down to its last dollar. Musk put his own cash into Tesla, and almost went broke because of it. He could have very easily thrown in the towel. Instead he bet on the company, and himself. It paid off. Tesla is a public company with $3.21 billion market cap. Its newest car, the Model S is a critical hit.