A British artificial intelligence researcher who left OpenAI for Anthropic in search of a more cautious approach has now quit the industry altogether, accusing both companies of “playing with our lives” in their race to build AI systems capable of improving themselves.
Jacob Coxon, 27, has spent the past three years working on pre-training, the stage at which models absorb vast amounts of data, first at OpenAI and then this year at its main rival, Anthropic.
In a post on X on Tuesday, he said neither company was acting responsibly. “They are racing straight to superintelligence and gambling with our lives,” he wrote.
"The people building AI earnestly believe that it could kill us all by the end of the decade," he warned, adding: "This is not a marketing stunt.”
His resignation comes as Anthropic prepares for a major stock market listing, after a summer marked by unauthorised hacking carried out by AI tools being tested at several laboratories.
Contacted by French news agency AFP, neither company responded immediately.
Leading AI groups say they are nearing the stage of “recursive self-improvement,” beyond which a model could design its own successor without human control.
According to Coxon, his colleagues use terms such as “crunchtime” and “endgame” to describe that trajectory.
He said Anthropic’s efforts were sincere, but argued that no company can responsibly develop AI that surpasses humans without government intervention or a co-ordinated slowdown.
"At OpenAI, many have not deeply internalized the civilizational stakes," he wrote. "At Anthropic, the stakes are well understood, but they are locked in a race to get there first - they believe no one else will act responsibly, so they must do it themselves, despite the risk."

