Elon Musk isn't just a man of the world – he's actively building worlds, whether it's on Mars or in your driveway. The billionaire entrepreneur and richest man in the world may be best known for Tesla, SpaceX and his Twitter antics, but his first ex-wife, Justine Musk, offers a more personal look at what makes Musk tick. Her stories paint a picture of a man who doesn't just dream big – he demands big.

"He would call very insistently," Justine said in Ashlee Vance's biography Elon Musk: Tesla, SpaceX and the Quest for a Fantastic Future, as reported by CNBC in 2018. "You always knew it was Elon because the phone would never stop ringing." 

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Musk, who fathered five children with Justine before their divorce in 2008, has always been known for his intensity. And for her, it was impossible to miss. "I do think of him as the Terminator. He locks his gaze on to something and says, ‘It shall be mine.'"

That determination didn't stop at building rockets or electric cars – it showed up in even the smallest of victories. While attending Queen's University in Canada, Justine and Musk took the same abnormal psychology class. After an exam, she scored a solid 97. Musk? He got a 98 – but even that wasn't good enough for him. "He went back to the professor and talked his way into the two points he'd lost," Justine said, securing a perfect 100. "It felt like we were always competing."

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This relentless drive was something Musk had nurtured from an early age. At 17, he left South Africa and moved to Canada to attend Queen's University. There, his dormmate Navaid Farooq quickly recognized Musk's laser focus, whether it was on strategy games or schoolwork.

"When Elon gets into something, he develops just this different level of interest in it than other people," Farooq told Vance. One example? The hours they spent playing Civilization, a popular strategy game. "Elon could lose himself for hours on end," Farooq said. It wasn't just about winning – it was about mastery.

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Farooq and Justine weren't the only ones to witness this all-consuming intensity. Musk himself admitted to it in a 2018 interview with journalist Kara Swisher. He described working 120-hour weeks to ramp up Tesla Model 3 production, saying, "Some weeks … I would just sort of sleep for a few hours, work, sleep for a few hours, work, seven days a week."

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