There are fewer local engineers to compete with in America than in China, so salaries are higher here as a result of the scarcity. So the optimal strategy for Chinese engineers is to come to the US and spend a few years earning big salaries at Google or Amazon or Apple, then move back to China to start their own companies.

That’s before you get into the amenities provided by Chinese municipalities, the lower cost of living, and the business friendly attitude of the current government.