Yes brain drain is an issue but quite a different one to the sustainability issues of global overpopulation. Its complex but I do think allowing people to study

Yes brain drain is an issue but quite a different one to the sustainability issues of global overpopulation. Its complex but I do think allowing people to study and work overseas does come back as a net benefit. Your doctor story can fall at a few hurdles - maybe they can't get the training at home, maybe they would turn to another industry just to get a reasonable salary if thats the option, maybe even if they can study overseas and return they don't have the opportunities to practice in their home country. I've seen all of these happen.