I hope I turn out to be wrong, but the most convincing explanation I've seen for the "why" is that the 1945-2000 period was an anomaly, and now we're reverting to the mean: despotic governments, frequent wars for territory, and massive wealth inequality leading to powerful oligarchies as the only other important political players aside from the despot. This was the norm for the overwhelming majority of human history and perhaps it was massively hubristic to think we had escaped it for good.