Elon Musk built a commercial rocket company from scratch and upended the auto industry as a high-profile evangelist for electric cars.
It has made him one of the richest people in the world.
In October, Musk completed a $44 billion deal to buy Twitter. But his time in charge of the social media platform has been rocky so far. After Twitter laid off thousands of employees, many of those remaining appeared to reject Musk's ultimatum to work "extremely hardcore," throwing the communications platform into utter disarray and raising serious questions about how much longer it will survive.
Musk, the CEO of SpaceX and Tesla, has been a risk-taker throughout his career. After making a dot-com fortune in the late 1990s and early 2000s, he bet it all on long-shot startups that have paid off.
"When something is important enough, you do it even if the odds are not in your favor," he once said.