

On that last point, Rome, Greece, China, Egypt, Spain & Portugal (from the Discoveries time), several Middle Eastern nations several times (from the Babylonians to the Persians and even the Arabs - back in the 12th Century the most advanced people in the World were Arabs, then known as Moors) and so on (if I remember it correctly the Mayan civilization fell before the Spanish Conquistadores got there, which would make it yet another one that fell to internal problems rather than external factors).
It’s a pretty common dynamic.
I’m Portuguese.
Portugal fell so far down that in the XX Century until 1974 it was under a Fascist dictatorship and was so poor it got food help from other nations in Europe (but the dictator sure liked to celebrate the “Time of the Discoveries”).
In our divergence of opinion, at least specifically when it comes to the timing of the fall of the US from its peak, time will tell.
PS: I don’t think the destruction due to internal unrest is merely from economic disparities - that’s just one of the symptoms. I think it’s mainly social, cultural and structural factors that create downstream problems like said economic disparities and keep on doing it because the problem is structural, not merely economical, and those things sustain themselves (for example, corrupt politicians aren’t going to put in place structures to fight corruption, quite the contrary). The fall is not merely from economic disparities, it’s because the whole society has grown “fat and lazy” - the spirit of people and, maybe more importantly, of the power elites who control how the country operates, is that they are “winners”, but all of that is anchored on the successes of their ancestors (in the US case, one example of that is American Exceptionalism), and that kind of posture doesn’t self correct and the nation itself is too big and powerful for it to be corrected by external actors. The whole thing is a bigger version of the very commonly story told all over the World in various variants about how Wealth goes in cycles of 3 generations: the first builds it, the second consolidates it and the third blows it away - having been brought up in wealth the third generation doesn’t have the same spirit as the people who built the wealth in the first place.
Anyways, this is just pseudo-Philosophical thinking and, as I said, time will tell.