They're not loyal to the country because the country has a history of not respecting people's loyalty.

It isn't about the money, it's about how Americans continue to demonize immigrants and have a tendency of treating people from certain countries as subversives even when they do show their loyalty.

These people are already here, doing research and propping up America's technological edge instead of their home country's. Driving away the people giving you your tech edge, in the name of protecting your tech edge, is obviously incredibly stupid.