He sold The Terminator script for $1 to guarantee the director's chair. Before that, he was driving trucks, working as a school janitor, and learning filmmaking by dissecting every Roger Corman picture he could get his hands on. Titanic in 1997 is where the bet paid off at scale: he reportedly forfeited his own salary to prevent the $200 million production from being cut, ran 15 weeks at the top of the U.S. box office, and took home 11 Oscars including Best Picture.
He's the only director to helm three films that each crossed $2 billion, but the Avatar franchise is testing that logic. Avatar: Fire and Ash grossed $1.48 billion against roughly $500 million in production and marketing costs, a thin margin for a studio tentpole. He's already openly discussing handing Avatar 4 to another director and training a successor for any films beyond that. At 71, the franchise he bet his legacy on may outlast his interest in running it.
The Terminator came to him in a fever dream while he had food poisoning in Rome, with his car being repossessed back in Los Angeles at the time. He later lost the franchise anyway: Linda Hamilton walked away with the rights in their divorce settlement, sold them to Carolco, and Cameron didn't direct another entry, though he returned as producer on Terminator: Dark Fate (2019). His fifth wife, Suzy Amis, played Rose's granddaughter in Titanic. His mother kept him alive through the lean years with Burger King coupons.