What about when it's both, because they learned many things about the United States that make a desire for disruption of the current status quo justified?
I think we're deluding ourselves if we think we can give people critical thinking and not have them question the consequences of colonialism, or slavery, or the industrial revolution, or manifest destiny, or homeland security, and which of those consequences should be kept and which should be torn down.
(There's a pretty good book on this subject, actually: among other things it touches on, The Myth of the Rational Voter [2007, Bryan Caplan] notes the stark difference in voting habits among those with and without a college education. Does that mean all college education includes indoctrination, or does it mean learning critical thinking causes people to think critically to similar conclusions, or perhaps both? And at another level of abstraction: if you're a policymaker and you want people to vote in the way they tend to do when not college educated, aren't there incentives to cast education itself into doubt?)