China definitely "leaks" a lot of talent to American companies - most AI papers that I've seen from respected Western universities include at least one Chinese name.
One challenge for China has been the university enrollment rate. While in Western countries half of each cohort has been going to university for decades, China is not there yet. In 2019, just 17% of Chinese adults have degrees compared to 44% in the US.
So the large Chinese population is offset by its relative lack of access to education, while the US can draw from its own highly educated population in addition to attracting the best and the brightest from the rest of the world, including China.
One challenge for China has been the university enrollment rate. While in Western countries half of each cohort has been going to university for decades, China is not there yet. In 2019, just 17% of Chinese adults have degrees compared to 44% in the US.
So the large Chinese population is offset by its relative lack of access to education, while the US can draw from its own highly educated population in addition to attracting the best and the brightest from the rest of the world, including China.