If we flip the snake so it goes along the political spectrum, with the biting ends being extremists, I suppose the fish does rot from the heads. Top-down versus bottom-up is a more-complicated situation, and I suspect it's closer to turbulence than anything monotonic.

The lack of competition from the Soviets is probably one of the bigger systemic causes. The cold war in no small part a war for hearts and minds in the democratic world. It was existentially important that the west believed in America, both the US itself and its allies. As long as the Soviets were around as existence proof for an alternate world order, the US needed at least visibly have its shit in order.

If today's clown fiesta had unfolded 50 years ago, well comrade, сегодня мы все говорили бы по-русски.