Hard not to see parallels with the end of the Roman empire. We know we could do better, we can't be bothered trying very hard and we'd rather moan about the good old days. All it needs is the more motivated (not very) barbarian hoarde to decide they'll do the social reconstruction we won't. Edit: I actually place great faith on coming generations. The kids are alright.
Putin thought he could be that horde. He is failing, and failing badly, in Ukraine.