> they think whatever they're doing must be "the best", irregardless of what <others> think

The word that comes to my mind is "arrogance". Is there a better fitting word? (Honest question, not a native speaker)

I think the proper academic term for it is "American exceptionalism"

Even American chauvinism.

As a fellow non north american, that seems quite fitting.

>I think culturally they think whatever they're doing must be "the best", irregardless of whatever the rest of the world thinks.

Funny, one could say the same about Europeans. And it'd be an equally sweeping and divisive claim.