Many people stayed in Western countries to get away from the stressful life and very competitive environment in China. If you make a decent salary in the US, you can live quite a comfortable, stress free life.
I can tell you that it is quite normal to have work meeting on Sunday mornings in China. This is the country you Westerners are trying to compete with. A nation full of hardworking people, and you think you can beat China in the long run? Those who don’t want to work as hard will prefer the Western lifestyle and that’s why they choose to stay there.
Nah postdocs make far below 100k in the US (OP was talking about researchers/scientists in academia), but certainly far less stressful and competitive compared to doing the same job back in China.