Elon Musk thinks personal robots could be a technological dream or a science fiction-style nightmare.

The world’s richest man talked about a robot-filled future during the Saudi-U.S. investment forum in Riyadh on Tuesday, where he acknowledged both the upsides and risks of having humanoid machine helpers.

“I think we’re headed to a radically different world. I think a good world, an interesting world,” Musk said, predicting there will be tens of billions of robots across the globe in the future.

“Everyone will want to have their personal robot,” added the billionaire, whose company Tesla unveiled the first prototype of its humanoid Optimus automaton in 2022. “You can think of it like — as though you had your own personal C-3PO or R2-D2 but even better.”

He also said that having personal robots “unlocks an immense amount of economic potential” and could possibly help the world economy blossom by tenfold.

But Musk, who joined Donald Trump in Saudi Arabia during the president’s trip to the Middle East, also acknowledged how the technology could go awry if we’re not careful.

“If we don’t do this right, you can have a James Cameron sort of movie, you know, ‘Terminator.’ We don’t want that one,” he said. “But having sort of a ‘Star Trek’ future would be great.”

The tech mogul has long maintained that a world full of personal robots is well within reach.

During Tesla’s “We, Robot” event in California last year, Musk said, “The Optimus will walk amongst you.”

He mused about machines that will be able to serve drinks, walk dogs, babysit or mow the lawn and said at a price of $20,000 to $30,000, they could be “something anyone could own.”

While in Riyadh, Musk also discussed the emerging autonomous car industry, saying, “You can think of future cars as being robots on four wheels.”

Tesla is reportedly hoping to launch a pilot program for its fleet of robotaxis in Austin, Texas, by June.

Watch Musk’s appearance at the Saudi-U.S. investment forum here: