Elon Musk stands in the Oval Office to attend a press conference with U.S. President Donald Trump, at the White House in Washington, D.C., U.S., May 30, 2025. REUTERS
Billionaire Elon Musk bade farewell to Donald Trump in an extraordinary Oval Office appearance Friday, sporting a black eye, brushing aside drug abuse claims and vowing to stay a "friend and advisor" to the US president.

As the world's richest person bowed out of his role as Trump's cost-cutter-in-chief, the Republican hailed Musk's "incredible service" and handed him a golden key to the White House.

But Trump insisted that Musk was "really not leaving" after a turbulent four months in which his Department of Government Efficiency (DOGE) cut tens of thousands of jobs, shuttered whole agencies and slashed foreign aid.

"He's going to be back and forth," said Trump, showering praise on the tech tycoon for what he called the "most sweeping and consequential government reform program in generations."

South-African born Musk, wearing a black T-shirt with the word "Dogefather" in white lettering and a black DOGE baseball cap, said many of the $1 trillion savings he promised would take time to bear fruit.

"I look forward to continuing to be a friend and advisor to the president," he said.

But many people were more interested in the livid black bruise around Musk's right eye.

Speculation about the cause was further fueled by accusations in the New York Times Friday that Musk used so much of the drug ketamine on the 2024 campaign trail that he developed bladder problems.

- 'Punch me' -

The SpaceX and Tesla magnate said that his son was to blame for the injury.

"I was just horsing around with lil' X, and I said, 'go ahead punch me in the face,'" 53-year-old Musk said. "And he did. Turns out even a five-year-old punching you in the face actually is..." he added, before tailing off.

Musk, however, dodged a question about the drug allegations.

The New York Times said Musk, the biggest donor to Trump's 2024 election campaign, also took ecstasy and psychoactive mushrooms and traveled with a pill box last year.

Musk, who has long railed against the news media and championed his X social media platform as an alternative, took aim at the paper instead.

"Is that the same publication that got a Pulitzer Prize for false reporting on the Russiagate?" said Musk, referring to claims that Trump's 2016 election campaign colluded with Moscow.

"Let's move on. Okay. Next question."

Later in the day, when a reporter asked Trump if he was "aware of Elon Musk's regular drug use," Trump simply responded: "I wasn't."

"I think Elon is a fantastic guy," he added.

The White House had earlier played down the report.

"The drugs that we're concerned about are the drugs running across the southern border" from Mexico, said Trump's Deputy Chief of Staff Stephen Miller, whose wife works for Musk.

Musk has previously admitted to taking ketamine, saying he was prescribed it to treat a "negative frame of mind" and suggesting his use of drugs benefited his work.

- 'Disappointed' -

The latest in a series of made-for-TV Oval Office events was aimed at putting a positive spin on Musk's departure.

Musk is leaving Trump's administration under a cloud, after admitting disillusionment with his role and criticizing the Republican president's spending plans.

It was a far cry from his first few weeks as Trump's chainsaw-brandishing sidekick.

At one time Musk was almost inseparable from Trump, glued to his side on Air Force One, Marine One, in the White House and at Trump's Mar-a-Lago resort in Florida.

The right-wing magnate's DOGE led an ideologically-driven rampage through the federal government, with its young "tech bros" slashing tens of thousands of jobs.

But DOGE's achievements fell far short of Musk's original goal of saving $2 trillion dollars.

The White House says DOGE has made $170 billion in savings so far. The independent "Doge Tracker" site has counted just $12 billion while the Atlantic magazine put it far lower, at $2 billion.

Musk's "move fast and break things" mantra was also at odds with some of his cabinet colleagues, and he said earlier this week that he was "disappointed" in Trump's planned mega tax and spending bill as it undermined DOGE's cuts.

Musk's companies, meanwhile, have suffered.

Tesla shareholders called for him to return to work as sales slumped and protests targeted the electric vehicle maker, while SpaceX had a series of fiery rocket failures.