Sure, I make more money here, but is it worth dealing with nonsensical immigration policies, haphazard funding cuts, crumbling infrastructure, completely random rulemaking, and demoralized colleagues facing severe and nonsensical budget cuts when various other countries with a good standard of living and competitive research labs make immigration very easy for skilled people like scientists?
It isn't specifically a Trump thing, but he's certainly proving to be the straw that broke the camel's back, and it's likely I'll go elsewhere once my postdoc appointment ends.
I can imagine that the decision is even easier for people from countries like China. Why deal with the stress of the government suddenly deciding that you aren't allowed to work at your institution anymore regardless of track record or background, (many chinese colleagues have been worried about the proposed legislation and it comes up often), when you can work at a similarly cutting edge institution back home? You just have to determine if the US being less authoritarian on certain things is valuable enough to put up with the awful treatment through the long immigration process.