Ms Koistinen said she wanted to make a “visible stand” against Musk personally.

A particular problem for Musk is that, before he seemingly created an enemy in Trump, he already had one in the grassroots social media campaign against his car-maker.

Protests, collectively dubbed #TeslaTakedown, have played out across the country every weekend since Trump took office.

In April, Tesla reported a 20% drop in car sales for the first three months of the year. Profits plunged more than 70%, and the share price went down with it.

“He should not be deciding the fate of our democracy by disassembling our government piece by piece. It’s not right,” protestor Linda Koistinen told me at a demonstration outside a Berkeley, California Tesla dealership in February.

Ms Koistinen said she wanted to make a “visible stand” against Musk personally.

“Ultimately it’s not about the tech or the Tesla corporation,” said Joan Donovan, a prominent disinformation researcher who co-organised the #TeslaTakedown protests on social media.

“It’s about the way in which the stock of Tesla has been able to be weaponised against the people and it has put Musk in such a position to have an incredible amount of power with no transparency.”

Another aspect of Musk’s empire that has raised the ire of his detractors is X, the social media platform once known as Twitter.

“He bought Twitter so that he had clout and would be able to – at the drop of a hat – reach hundreds of millions of people,” Ms Donovan said.

There is another possibility here though.

Could Musk’s high-profile falling out with Trump help rehabilitate him in the eyes of people who turned against him because of his previous closeness to the president?

Patrick Moorhead, chief analyst at Moor Insights & Strategy, thinks it could.

“We’re a very forgiving country,” he said.

“These things take time,” Mr Moorhead acknowledged, but “it’s not unprecedented”.

Ms Swisher likened Musk’s personal brand to that of Microsoft co-founder Bill Gates more than two decades ago.

She said Gates was once regarded as “the Darth Vader of Silicon Valley” because of his “arrogant and rude” personality.

Today, despite his flaws, Gates has largely rehabilitated his image.

“He learned. He grew up. People can change,” Ms Swisher said, even though Musk is “clearly troubled”.

The problem for Musk is the future for him and his companies is not just about what he does – but what Trump decides too.

And while Trump needed Musk in the past, not least to help fund his presidential race, it’s not so clear he does now.

Noah Smith, writer of the Noahpinion Substack, said Trump’s highly lucrative foray into cryptocurrencies – as unseemly as it has been – may have freed him from depending on Musk to carry out his will.

“My guess is that this was so he could get out from under Elon,” he said.

In Trump’s most menacing comment of the day, he suggested cutting Musk’s government contracts, which have an estimated value of $38bn (£28bn).

A significant chunk of that goes to Musk’s rocket company SpaceX – seemingly threatening its future.

However, despite the bluster, Trump’s warning may be a little more hollow than it seems.