8 major takeaways from the explosive new book about Elon Musk that lifts the lid on the world's richest person

The book explains how Musk's moods can swing wildly.

"He has numerous minds and many fairly distinct personalities," Grimes told Isaacson. "He moves between them at a very rapid pace. You just feel the air in the room change, and suddenly the whole situation is just transferred over to his other state."

Isaacson said that throughout his time with Musk, he'd also witnessed the billionaire's emotional volatility, saying he'd switch between "light and dark, intense and goofy, detached and emotional."

"When we hang out, I make sure I'm with the right Elon," Grimes said. "There are guys in that head who don't like me, and I don't like them." These vary from the version of him "who's down for Burning Man and will sleep on a couch, eat canned soup, and be chill" and his so-called "demon mode" — "when he goes dark and retreats inside the storm in his brain."

During these periods, Musk is likely to unleash his rage on employees or order up a work surge, according to Isaacson. Grimes said despite the darkness associated with "demon mode," it's also the mode where he "gets shit done."

One character who appears frequently throughout the book is Elon Musk's father, Errol Musk.

The biography is peppered with descriptions of incidents where Elon Musk claims his father bullied and demeaned him (something Errol Musk has denied), as well as comments from Elon Musk's former girlfriends and wives about how Errol Musk ultimately influenced his son's personality and outlook on the world.

After his parents divorced, Elon Musk originally lived with his mother before spending about seven years living with his father in Pretoria from the age of 10.

"It turned out to be a really bad idea," Elon Musk told Isaacson. "I didn't yet how how horrible he was."

His younger brother Kimbal Musk told Isaacson that their father had "zero compassion" and often "went ballistic."

"It was mental torture," Elon Musk told Isaacson. "He sure knew how to make anything terrible."

Elon Musk's mother, Maye Musk, said there was a fear her son "might become his father."

Both Elon and Kimbal Musk no longer speak to their father, Isaacson wrote.

But the years that he spent with his father have somewhat shaped Elon Musk's personality, according to the book. 

"I think he got conditioned in childhood that life is pain," Grimes, Elon Musk's former girlfriend, told Isaacson. She also noted that because of how his father brought him up, Musk sometimes lets himself be treated badly and "associates love with being mean or abusive." 

Justine Musk, Elon Musk's first wife, told Isaacson said that during their arguments, Elon would belittle and insult her, calling her a "moron," an "idiot," or "stupid and crazy."

"When I spent some time with Errol, I realized that's where he'd gotten the vocabulary," Justine Musk told Isaacson. 

Ex-wife Talulah Riley also told Isaacson that Errol Musk's treatment of his son "had a profound effect on how he operates."

"Inside the man, he's still there as a child, a child standing in front of his dad," she said.

Musk is well known for his "hardcore" work mindset, which in some cases involved sleeping and eating in the office. His late-night habits seem to stem from his childhood, when he would stay up until 6 a.m. reading, Isaacson wrote.

While he worked at Zip2, his first business, Musk and his brother slept in the office, showered at the YMCA, and mainly ate at Jack in the Box, the book said. One early Zip2 employee told Isaacson that he even had to tell Musk to go home and shower before customer meetings.

"At Zip2 and every subsequent company, he drove himself relentlessly all day and through much of the night, without vacations, and he expected others to do the same," Isaacson wrote. "His only indulgence was allowing breaks for intense video-game binges."

Musk has applied the same intensity to other aspects of his life, too, including learning to fly planes. "I tend to do things very intensely," he told Isaacson.

Musk expects his employees to display the same workaholic nature. At banking company X.com, which later became PayPal following a merger, he told staff that the site would launch to the public on Thanksgiving weekend and "prowled the office each day, including Thanksgiving, in a nervous and nervous-making frenzy and slept under his desk most nights," Isaacson wrote.

After buying Twitter more than two decades later, he told its staff to commit to an "extremely hardcore" work schedule with "long hours at a high intensity" if they wanted to keep their jobs.

Horror stories about working with Elon Musk are hardly a new phenomenon — from quickly laying off over half of Twitter's workforce to forcing some Tesla workers to work through Thanksgiving — working at one of his companies has become the stuff of urban legends. And it turns out tensions were often near a boiling point, even at Musk's first startup.

Musk's brother once "tore off a hunk of flesh" from Musk's hand while the brothers wrestled on the floor in Zip2's office back in the 90s, according to Isaacson. The biographer said the two men would wrestle during periods of "intense stress."

Similarly, Musk's college dorm-mate quit working at Zip2 just six weeks after starting at the company because he couldn't handle working with Musk, according to the book.

"I knew I could either be working with him or be his friend, but not both," Musk's longtime friend and former dorm-mate, Navaid Farooq, told Isaacson.

Musk later explained the reasoning behind his intensity after he chewed out a SpaceX worker who had lost his child the week prior.

"I give people hardcore feedback, mostly accurate, and I try not to to do it in a way that's ad hominem," Musk told Isaacson. "I try to criticize the action, not the person. We all make mistakes. What matters is whether a person has a good feedback loop, can seek criticism from others, and can improve. Physics does not care about feelings. It cares about whether you got the rocket right."

During stressful periods at work and in his personal life, Musk would stay awake at night and vomit, Isaacson wrote.

The biographer said that at one point Musk's stomach pain had a doctor checking for appendicitis. 

In 2008 when Tesla was facing the potential of bankruptcy, Musk's wife at the time, Talulah Riley, told Isaacson she worried the stress would cause Musk to have a heart attack.

"He was having night terrors and just screaming in his sleep and clawing at me," she said. "It would go to his gut, and he would be screaming and retching. I would stand by the toilet and hold his head."

Musk's ex-girlfriend Grimes says she recalls similarly sleepless nights during her relationship with the billionaire.

Musk appears to seek out these periods of high stress, according to some. 

"You don't have to be in a state of war at all times," Shivon Zilis, the mother of two of Musk's children and a director at Neuralink, told Musk when he was gearing up to buy Twitter. "Or is it that you find greater comfort when you're in periods of war?" 

Musk told Zilis it's one of his "default settings."

"I guess I've always wanted to push my chips back on the table or play the next level of the game."

Though, Musk has admitted to Isaacson his intensity has taken a toll on him physically.

"From 2007 onwards, until maybe last year, it's been nonstop pain. There's a gun to your head, make Tesla work, pull a rabbit out of your hat, then pull another rabbit out of the hat," Musk told Isaacson in 2021.

"You can't be in a constant fight for survival, always in adrenaline mode, and not have it hurt you. But there's something else I've found this year. It's that fighting to survive keeps you going for quite a while. When you are no longer in a survive-or-die mode, it's not that easy to get motivated every day," he added.

Isaacson interviewed many of the women Musk used to date or be married to. It becomes clear that Musk can be a difficult person to date because of a range of factors, including his laser focus on his businesses and his lack of empathy and social awareness.

"Elon and I were used to having big arguments in public," Justine Musk told Isaacson. "I don't think you can be in a relationship with Elon and not argue."

Musk postponed his honeymoon with Justine by months so that he could sort out X.com's merger with PayPal, and they had to cut it short amid turmoil at the company.

Justine told Isaacson that Elon Musk told her to dye her hair blonder and that she felt like she was being turned into a "trophy wife."

"I met him when he didn't have much at all," she told Isaacson. "The accumulation of wealth and fame changed the dynamic."

"The strong will and emotional distance that makes him difficult as a husband may be reasons for his success in running a business," she added.

Meanwhile, his emotional volatility and inability to understand other people's emotions at times can be hard to deal with, Grimes told Isaacson.

Isaacson wrote that Musk sent a picture of his then-girlfriend Grimes having a C-section when she had X to their friends and family, including her father and brothers. Grimes said he was "clueless" about why she'd be upset about it.

Though the book describes Musk's volatile relationships with many people, including relatives, friends, partners, and business associates, it also details how he can be tender at times. In particular, Isaacson paints a picture of Musk as a doting father to X AE A-XII, also known as "baby X," his first child with Grimes.

Isaacson wrote that X "had an otherworldly sweetness that calmed and beguiled Musk, who craved his presence. He took X everywhere."

Musk also moved in with his father aged 10 because he didn't want him to be lonely, Isaacson wrote. Musk's cousin Peter Rive told Isaacson that playing "Dungeons and Dragons" together as a child brought out the "incredibly patient" and "beautiful" parts of Musk's personality.

When a close friend of Musk's ex-wife Talulah Riley died in 2021, he flew over to England to be with her, "and he just made me laugh instead of cry," she told Isaacson.

While Musk has cut off communication with his father, Errol Musk, Isaacson said the billionaire's political stance is beginning to mimic his father's.

Isaacson said Errol's sons were sometimes off-put by their father's political rants. For example in 2022, Errol sent Musk an email in which he called the COVID-19 pandemic "a lie" and dubbed President Joe Biden a '"freak, criminal, pedophile president' who was out to destroy everything that the US stood for, 'including you,'" Isaacson wrote.

The biographer said Musk had begun to show a similar propensity which was in part triggered by his daughter Vivian Jenna Wilson's decision to cut ties with him. Isaacson said that Musk blamed the disconnect on the "woke mind virus."

Over the past few years Musk has gone from from supporting the Democratic party to publicly dissing President Joe Biden, reposting anti-transgender content on X, and promoting conspiracy theories.

"Musk's tweet showed his growing tendency (like his father) to read wacky fake-news sites purveying conspiracy theories, a problem that Twitter had writ at large," Isaacson wrote of Musk's decision to post about a conspiracy theory related to the attack on Nancy Pelosi's husband.

And, like his father, Musk's politics have been met with distaste from much of his family.

"It's not okay," Kimbal Musk told his brother after he tweeted "My pronouns are Prosecute/Fauci." "It's not funny. You can't do that shit."

The biography is in stores now.