Many young Chinese who were educated in the US feel this way, so it's not a generational thing. This is a cultural tradition stretching back many thousands of years. The world view of a person from China is very different than that of an American.
Also, consider that an AI researcher returning to China is likely going to be in the top 1% of society. Dictatorial societies tend to be pretty good for the people at the top. The Chinese startup market is hotter than the US at this point too; and it's basically restricted to people born in a handful of Chinese cities. The Chinese government intentionally stacks the deck to get them to return.