It used to be every generation of Americans had its subset of youth who become infatuated with Communism, for example. They generally grow out of it and come to appreciate their global standing once they graduate college and accumulate some wealth.
Europeans are accustomed to being more mobile and studying abroad seems to be almost expected. America is a very insular culture by comparison; depending on academic program a lot of schools don't have meaningful study abroad programs ("let's go spend a week attending some lectures in London then go home") and support for things like working holiday visas is pathetic. We don't have anything like Erasmus. The only people I ever seem to meet who have traveled more than a few hundred miles from home have only done so on deployment with the military.
In aggregate we know virtually nothing about the rest of the world, so it's easy for disillusioned kids to be convinced that their minor dissatisfactions are on the level of human rights violations and that North Korea or ISIS-held Syria are favorable by comparison.
Note that there are bad people and bad emperors and everything in between, having vastly different abilities to affect people. They are hardly equivalent, though bad they all are.