I think it's quite likely, but unknowable, that folks would accept the income:cost of living ratio of the US if it came with the associated sociological benefits. I think you're underestimating how disproportionately impoverished many people around the world are.
Except that the Chinese person is a prisoner in their own country, and the American could move to China to have a higher quality of life outside of the polluted cities.
You're right that a few people do, although I think most people realise how deeply fortunate we all are to have won to at least some extent a genetic and [entirely separate] geographic lottery.
