I think that's very possible, but I'm not sure how best to distinguish incredible delusions of self-importance(/nationalism) from imperialist attitudes without the ability to act on them (well, we still invade places, but only if the US tells us to). Maybe this is more obvious from the outside?

Certainly, and obviously this is 100% anecdotal and I’m not a sociologist. I just look at things like the UK’s trans panic (worse there even than the States) as a colonial practice turned inward, where a body politic forcibly dictates identity/social role to a less-privileged underclass.