Over the past 15 years the Chinese government has had quite a lot of success encouraging both high profile and more junior scientists to return to China (some of whom left as children) with good faculty positions and large research support.

Certainly many of the wealthy want to move some assets out of the country (that's the "richest" you discuss) but few are moving wholesale as happens with, say, many wealthy Russians.

1) Disregarding reality for a second, consider 2 populations (one small, one large) and then assume identical probability for a student to study abroad, say one in 30 for example. Of course there will be more student from the populous to the less populous nation... Stated otherwise, how many exchange student have you seen from Luxembourg?

2) To explain richest: it is quite conceivable that kids of the rich have better access to education, so seeing a student from China (or anywhere really) has a statistical tendency of being correlated with wealth anyway.

3) Considering best, brightest: these will have a higher probability of getting permission and / or funds to study abroad. On the other hand, have you ever compared the visiting Chinese students with those that stayed in China? Perhaps the best and brightest are staying in China...

4) In order to conclude the higher quality of education in the West, you assume that the student's motivation to study in the West is it's supposed higher quality of education. This is a circular reasoning. This may be true, or false. Other reasons for studying in the West could be they perceive it like most students perceive studies abroad: an exercise in self-reliance, temporary freedom from family obligations, a vacation in what they might perceive as Disney World / Hollywood to be combined with their studies, ... this would certainly clarify the observation of "richer" Chinese students.

Most of these variables are outside of my measurement scope, so I can make no assertions on their veracity or lack thereof. I only wish to convey that the statement you made seems to make a lot of assumptions that I consider them dangerous and naive to blindly assume, if such assumption happens collectively in order to pat each other's backs...

That works both ways. China has a so called 1000 talents plan. Effectively a lottery for USD ~$3m for a person with a PhD level education and a passable business plan.

I personally knew one exceptional foreign chemist who, after living in China for 15 years, finally dared to do "deal with the devil" and managed to land a defence contract. She was just 27 when she started her business as a continuation of her PhD.