Actually there are a LOT of Chinese and Indian entrepreneurs I know who moved to the US, worked here, and especially back in India are now building SV-style companies there. Or are putting parts of their global businesses there -- given how expensive labor is in the US and especially SV, it's a huge competitive advantage to be from, say, Ukraine and be able to set up a great engineering organization there.

I agree it makes less sense for an individual worker to move back (unless there are family or other concerns).