I see it more as a brain drain. I wonder how the world would be if those extremely talented people have stayed in their home countries and contributed to the local economies and development of the respective countries rather than contributing to the American imperialism.
Return immigrants are a non-negligible plus for the countries the people returned to because they saw other ways of working and lives and approaches and they seed their original countries. I do agree brain drain can be rough, but cross-polination of skills is super useful.