Photograph by Mark Mahaney for TIME

The richest man in the world does not own a house and has recently been selling off his fortune. He tosses satellites into orbit and harnesses the sun; he drives a car he created that uses no gas and barely needs a driver. With a flick of his finger, the stock market soars or swoons. An army of devotees hangs on his every utterance. He dreams of Mars as he bestrides Earth, square-jawed and indomitable. Lately, Elon Musk also likes to live-tweet his poops.

“He is a humanist—not in the sense of being a nice person, because he isn’t,” says Robert Zubrin, founder of the Mars Society, who met Musk in 2001, when the young, newly minted dot-com millionaire sent a large unsolicited check to the organization. “He wants eternal glory for doing great deeds, and he is an asset to the human race because he defines a great deed as something that is great for humanity. He is greedy for glory. Money to him is a means, not an end. Who today evaluates Thomas Edison on the basis of which of his inventions turned a profit?”