"Why did Chinese citizens build ChatGPT in the US and let US companies pay for the computing power?" ;)
"China can draw on a talent pool of 1.3 billion people, but the United States can draw on a talent pool of 7 billion and recombine them in a diverse culture that enhances creativity in a way that ethnic Han nationalism cannot." - Lee Kuan Yew
Salaries in the US are a multiple of what they are inside China. And for the top 0.1% on the skill scale, the factor is probably 10x to 100x. Now not everyone reaches that level and many fail and burn (or suffer through un-payable student loans for many years), but still the few people that make it into OpenAI are probably paid 100x of what they could earn in their hometown in Asia.
https://arxiv.org/abs/2005.14165
Jokes aside - you can replace Chinese with Indian too and still the same answer holds. There is something magical about Silicon Valley and it is definitely not about the salaries. Fwiw, bytedance pays in the 7 figures usd in Beijing!