Then there's Elon Musk...who is apparently thinking about a new company to sell bricks made from the mud from his tunnel boring company.
Elon Musk doesn't appear to be motivated by profit and therefore he doesn't need a hobby. Besides, what cooler hobby could there be than building rockets.
When you say he's in it for power, that sounds like you think of power as meaning power over other people, but why can't he be primarily motivated by seeking power over nature - which living on Mars might amount to the ultimate example of?