"I think there was like literally one week where I actually worked 120 hours and just didn't leave the factory. I didn't even go outside," Musk told Leslie Stahl on Sunday's "60 Minutes" on CBS.
"I wanted to make it clear to the team. They needed to see that however hard it was for them, I would make it worse for me," the 47-year-old entrepreneur told Stahl.
Musk said he worked on the floor fixing problems and slowdowns in the assembly line as Tesla struggled to ramp up production of its Model 3 car. The delays in production pushed the car-maker to the brink, according to Musk: "It was life or death. We were losing $50 [million], sometimes $100 million a week. Running out of money.
"Yeah. That's scary," Musk added.
To help speed up production, Tesla built an extra assembly line under a tent in the parking lot at its Fremont, California factory.
It was "a pretty miraculous effort by the team to create a general assembly line out of nothing in three weeks," Musk said. "So those, you know, betting against the company were right by all conventional standards that we would fail. But they just did not count on this unconventional situation of creating an assembly line in a parking lot in a tent."
Asked if he wants to buy plants that might be idled by GM, Musk nods: "It's possible that we would be interested if they were closing a plant or not use it—that we would take it over."
The production line in the tent increased Tesla's output by 50 percent, Musk told Stahl. In October, Tesla announced it had swung to profitability.
The combined efforts of Tesla employees to keep the company alive is worthy of praise the company doesn't get, Musk said.
"There's been relentless criticism, relentless and outrageous and unfair. Because what actually happened here was an incredible American success story," Musk said to Stahl. "All these people work their ass off day and night to make it happen. And they believe in the dream. And that's the story that really should be told."
It's not the first time Musk has talked about his leadership strategy.
Musk told "CBS This Morning" host Gayle King in April that he sometimes sleeps at the Tesla factory to show his team that he does't ask them to do anything he won't do himself.
"Yeah, I'm sleeping on the factory floor, not because I think that's a fun place to sleep. You know. Terrible," Musk told King. "I don't believe like people should be experiencing hardship while the CEO is, like, off on vacation."
Musk hosted the November 2017 Tesla earnings call from the Gigafactory, Tesla's battery production facility in Nevada, because that's where he was working, correcting production delays, he said.
"I move myself to wherever the biggest problem is in Tesla," said Musk. "I really believe that one should lead from the front lines and that's why I'm here."
At the time, Musk talked of his hands-on work at the factory. "I am personally on that line, in that machine, trying to solve problems personally where I can," Musk said. "We are working seven days a week to do it. And I have personally been here on zone 2 module line at 2:00 a.m. on a Sunday morning, helping diagnose robot calibration issues. So I'm doing everything I can."
Not everyone agrees with Musk's methods.
Thrive Global founder, author and sleep advocate Arianna Huffington said Musk's extreme working hours were irresponsible and counterproductive.
"Working 120-hour weeks doesn't leverage your unique qualities, it wastes them. You can't simply power through — that's just not how our bodies and our brains work," Huffington wrote in an open letter to Musk. "Nobody knows better than you that we can't get to Mars by ignoring the laws of physics. Nor can we get where we want to go by ignoring scientific laws in our daily lives."
And there have been claims that the working conditions at Tesla are dangerous and extreme. However, the CEO dismissed the allegations. "I don't think that's correct," Musk told Stahl, after she mentioned reports of toxic fumes, stress injuries and ambulance calls at Tesla. "I was literally living in the factory. If these — if there's, like, toxic fumes, I'm breathing them. Okay?"
Musk seems to wear the long hours, at least, as badge of honor. As he said on Twitter recently, 40 hour work weeks weren't sufficient for anyone with grand ambitions.