The late Apple cofounder Steve Jobs didn’t shy away from speaking about his experiences with LSD. The entrepreneur spent his early 20s searching for the meaning of life through meditation, traveling, and, sometimes, LSD.

“I came of age at a magical time,” Jobs told his biographer Walter Isaacson.

The billionaire described taking LSD as a “profound experience” and one of the most important things in his life.

“It reinforced my sense of what was important — creating great things instead of making money, putting things back into the stream of history and of human consciousness as much as I could,” Jobs said.

In the two-year period between 1972 and 1974, Jobs used LSD 10 to 15 times before he stopped for good, according to a questionnaire he filled out in 1988 for government security clearance.

OpenAI cofounder and CEO Sam Altman said in a September podcast appearance on “Life in Seven Songs,” that doing psychedelics was one of the most transformative experiences of his life.

The billionaire said he used to be a “very anxious, unhappy person” and now feels “calm.”

“If you had told me that, like, one weekend-long retreat in Mexico was going to significantly change that, I would have said absolutely not,” Altman said in the podcast. “And it really did.”

While the CEO said he had used psychedelics at Burning Man, he said those experiences had been rare and less impactful. He said the “life-changing” experiences have been ones where he travels for the experience and takes psychedelics with a guide.

Altman has invested in a number of medical startups, including one focused on psychedelics. The billionaire served as the board chairman of a startup called Journey Colab that aims to help people suffering from addiction with the development and application of clinical psychedelic drugs for therapy.

Google cofounder Sergey Brin has reportedly consumed psilocybin, the active ingredient in magic mushrooms, according to a Wall Street Journal report.

While Brin hasn’t confirmed his usage publicly and didn’t respond to a request for comment from Business Insider, the cofounder previously attended Burning Man with Eric Schmidt to see if Schmidt had it in him to be Google’s CEO.

The cofounder has also funds into a nonprofit investment firm called Catalyst4, which has pledged $15 million to Soneira, a startup studying the effects of a hallucinogenic mental health treatment.

Musk hasn’t spoken about personally using psychedelics, but The Wall Street Journal reported earlier this year that the billionaire has used LSD and magic mushrooms, among other illegal drugs.

Musk is also a frequent attendee at Burning Man. One of his friends once told The New York Times that he’s been on “mild exploratory journeys” with Musk.

The Tesla CEO has publicly discussed the benefits of psychedelics, including in a response to a tweet from Altman on the subject.

Musk told Don Lemon in an interview in March that he used “a small amount” of Ketamine about once every other week, and sometimes goes several weeks without using it. Ketamine is classified as a dissociative anesthetic that has some hallucinogenic effects. It has been increasingly used as a depression treatment.

Musk said he used ketamine when he was in a “negative chemical state,” such as depression, and considers it a better option than SSRIs. When asked if he abused the drug, Musk told Lemon he doesn’t think so.

“If you use too much ketamine, you can’t really get work done, and I have a lot of work,” Musk said in the interview.