After success with his early internet start-ups, Elon Musk became what everyone in the late 1990s wanted to be: a dotcom millionaire.

In 1999, Musk sold his first company, Zip2, to Compaq for roughly $300 million. After that, he went on to start X.com, which eventually became PayPal. In 2002, eBay purchased PayPal for $1.5 billion.

In 2002, he founded SpaceX, which is worth an estimated $33 billion, and in 2003, he founded Tesla, which has a current market cap of about $57 billion.

Though Musk had much success, he has not had a lot of time off. In fact, according to Musk, "vacations will kill you."

Why the aversion to vacations? It's partially due to work. Musk said on Recode Decode that to successfully build his start-ups, he would have to work over 100 hours a week.

And not much has changed.

In 2018, for example, Musk was sleeping on the Tesla factory floor in an effort to catch up production on the Model 3 cars.

"I don't have time to go home and shower," he told Gayle King on "CBS This Morning."

"I don't believe people should be experiencing hardship while the CEO is, like, off on vacation," he said.

In addition to working all the time, Musk — who says he has only tried to take off a handful of times — has had terrible luck when it comes to vacations.

In 2015, Musk said that he had only taken off twice in more than a decade, and both times were problematic.

"In the last 12 years, I only tried to take a week off twice," he said in 2015 on Danish television. "The first time I took a week off, the Orbital Sciences rocket exploded and Richard Branson's [Virgin Galactic] rocket exploded in that same week.

"The second time I took a week off, my rocket exploded," Musk said.

"The lesson here is, don't take a week off."

Even before that, when Musk tried to take his first adult vacation, his honeymoon with first wife Justine in September 2000, he got bad professional news.

At the time, he was CEO of X.com, and company executives were not pleased with his leadership. While Musk was on the plane with Justine, executives delivered a letter of no-confidence to the company's board, pushing Musk out as CEO, and replacing him with Peter Thiel. When he arrived for his honeymoon in Sydney, Australia, Musk had to immediately fly back to Palo Alto, California, according to the book "Elon Musk: Tesla, SpaceX, and the Quest for a Fantastic Future," by Ashlee Vance.

But perhaps Musk's most traumatic vacation experience came when he and Justine decided to try and go on their honeymoon again that December.

Musk planned a two-week trip to Brazil and South Africa. While in South Africa, Musk contracted the most severe form of malaria. After two hospitals misdiagnosed him, he "came very close to dying," said Musk in "Elon Musk," before being properly treated in the nick of time.

"That's my lesson for taking a vacation," Musk said in the book. "Vacations will kill you."

Since Musk's disastrous trips, he has reportedly been on at least two vacations, including one to Chile and one to Australia.

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