This reminded me of the book "Guns, Germs, and Steel". In it scientific development progressed a bit better in europe when they were broken into multiple competing states (and after the catholic church stopped being the central government). Since when one country decided to oppress their intellectuals, they could move somewhere friendlier.
As far as I can tell the U.S. has had a long love-hate relationship with it's intellectual population. People too smart are somewhat untrusted. (At least I've run into that problem occasionally, especially around fundamentalist types.)
Additionally as the religious fundamentalist and fascist types are trying to gain control of the government it's getting more difficult to try and express dissent, or even think for yourself.
Then the question is should one stay in the US and struggle to maintain a free and open society, or is it time to move on to greener pastures, and leave the US to the exploited workers and super-rich exploiters.
Perhaps if there was enough "brain drain", the US would loose it's place as economic superpower (followed by loosing it's military superpower status as they lose the ability to pay for a large standing military.