American with a more serious answer: I’d pick Lincoln picking a slaver as his VP and then getting shot. Functionally destroyed every good thing he did. Revealed the truth of “compromise” in 1865 and liberals still haven’t learned it.

Since I’m Pasta-American: Italy in general. Going from ruling “the world” to being ruled by a combo of the french, the popes, proto-hyper-capitalists, and vikings. Then they didn’t even have it in them to fully conquer to pope after uniting the peninsula, in the mid/late 1800s. Then stumbling through the late 1800s, helping invent fascism, rejecting the huge support communists gave for freeing them from the upside down man…

Not my nation, and not “stupid” but kind of hard to process for a young American (Like I was when I first read about it): the Taiping Heavenly Kingdom happening because of the Qing state’s decline, their civil service system becoming corrupt, peasant-middle class disaffection, and the influx of Christian missionaries, etc etc. All leading to a guy claiming to be Jesus’ brother and leading a revolt. Late Qing in general was a cluster. Shocked it didn’t collapse into the warlord era earlier.

Bonus to all Americans that still think Bush etal was a good president/did the right things after 9/11. Don’t know how you can look at America now and say “yeah it was right to invade the wrong country twice and waste all these resources and disaffect so many abroad and at home” (and kill people abroad too, but hoping for that from Americans might be asking too much).