Mate, american history is so recent it can basically be covered in detail in a single middle school year. The US has had zero real external threats post revolution, so much land and resources it can afford to burn them for fun and was the recipient of the entire world's brain drain. Take a random south american country and it'll have a dramatically harder history. Including the part where the US probably attacked them or manipulated their elections.
> The US has had zero real external threats post revolution
The US had external threats by Great Britain, Spain, Mexico, Barbary states, Native peoples, Japan, USSR, Italy, and Germany. They all took military and political action against the United States.
South american countries also have a fascinating history! But I'm not sure how that diminishes anything of the USA's struggle for existence. If anything, it heightens the fact that the founding of the USA is largely a miracle where the right people were in the right place at the right time. The fact that the USA's government has endured is by itself worth study.
and why limit it to external threats? are external threats the only one that threaten a country?