There's also a zero sum, race dynamic between geopolitical rivals. The US will not permit China to win anything if they can prevent it. The destruction of humanity is only a possibility and China will continue to develop it anyway if the US slows down.
So the choice is: negotiate an unverifiable treaty (I.e. there's no way to verify compliance), or keep going as you are and try your best to not cause the destruction of humanity without slowing down.
I don’t think OpenAI, Anthropic, nor Google are building their tech because they want to beat the Chinese. They’re building it because they want to hold the monopoly in the west (ie make lots of money).
The China argument is just a convenient scapegoat to convince the public that this isn’t just about greed.