> Unfortunately, the attractiveness of becoming a U.S. citizen is waning because (1) current U.S. policies on science are extremely unfavorable to foreign researchers and (2) other countries are making it much more desirable to remain a citizen there than to become a U.S. citizen (this is a net win for humanity though)

Don't forget (3) being tax compliant as a US citizen/perm resident. Since Obama made this worse with FACTA, Trump now with GILTI, etc., US citizenship and permanent residency has become extremely hostile to expats.