Chinese academia is way too competitive and exhausting for your American scientists. How many American grad students and postdocs are willing to work 6-7 days a week and have their lab meeting held on Sunday, which is becoming a common occurrence now?
These are some of the most hardworking people out there (and you can see them carrying their work ethic overseas as grad students and postdocs in Western universities) and churning out top tier scientific publications every year. These are the people you are going to compete against. If you think the “publish or perish” pressure is bad in Western academia, then in China this is ramped up to the next level.
Finally, connections are very important in China, even more so than in America and Europe. Much of the institute’s funding is going to be received by the heads of the departments, who then distribute the funds to the individual labs underneath them. Unless you are already a well-renowned scientist, you are going to be competing against your peers who have actual connections to the senior figures in the department.
Chinese science is very well funded, but the competition is also extreme, just like most industries in China. You don’t publish well, you won’t survive. Europe may be lacking in their funding, but their work culture is also more relaxed and suited to Westerners.
I have several friends with PhD who emigrated to the US and loved it there because, according to them, at least it is nowhere near as exhausting as they had it in China. They actually have the time to enjoy their weekends, a luxury you won’t get in Chinese academia.