I'm not from the US but my understanding is that the way US history is taught in schools and sometimes even colleges is heavily whitewashed and romanticized. Pupils are also repeatedly taught "allegiance ... to the republic, one nation under god" (how dystopian). It is very difficult to accept that your entire understanding (and thus love) of the country you live in is at best heavily doctored and at worst just a total sham perpetrated by the elites.

How easy it is to make people believe a lie, and how hard it is to undo that work again!