Bill Gates took a few jabs at fellow billionaire Elon Musk in a new interview, saying he does not view the Tesla CEO as a "great philanthropist" at this point while dismissing the SpaceX founder's efforts to go to Mars as a waste of money.

The BBC asked the Microsoft co-founder in a recent sit-down whether he believes Musk will ever join the club of mega-rich donors like Gates, Berkshire Hathaway's Warren Buffett, and Amazon's Jeff Bezos in pledging to give away most of their wealth.

"Yeah, I think someday he'll be a great philanthropist," Gates said of Musk, conceding, "Obviously, you know, things like Tesla are having a positive impact — even without being a form of philanthropy."

"But at the end of the day, I don't think he'll — other than going to Mars a few times … I don't think he'll spend it on himself," Gates continued. "So yeah, someday I think he will join the rank of philanthropists using his ingenuity."

Gates told BBC interviewer Amol Rajan that he does not believe Musk's mission to colonize the Red Planet is a good use of funds, saying providing vaccines to people in need should be a higher priority.

"It's actually quite expensive to go to Mars," Gates said. "You can buy measles vaccines and save lives for $1,000 per life saved, and so it just sort of grounds you, as in — don't go to Mars."

Musk and Gates have been at odds in the past.

Last year, Musk confirmed he turned Gates down on an offer to collaborate on philanthropic efforts to combat climate change, after leaked texts between the two showed Musk telling Gates he can't take him "seriously when you have a massive short position against Tesla, the company doing the most to solve climate change."

A short position is a bet against a stock.

Musk then trolled Gates with a vulgar tweet comparing a photo of the Microsoft co-founder to a pregnant man emoji. Musk later said he was "moving on from making fun of Gates for shorting Tesla while claiming to support climate change action."

But since then, Gates has also praised Musk, and said publicly that the Tesla CEO should not be underestimated following his $44 billion takeover of Twitter.

"You wouldn't want to underestimate Elon. What he did at Tesla is amazing, helping with climate change, what he did at SpaceX," Gates told the "Today" show in May 2022. "Will he, this time, make that improvement? … Elon thinks he can improve Twitter. Well, I don't know specifically what he'll do, but there's an opportunity and we need innovation in that space."