Eight decades later, and all those lessons have been forgotten. Self-interested and shortsighted leaders have risen to the tops of many nations, and nationalistic rhetoric is gaining popularity again.
https://en.wikipedia.org/wiki/Strauss%E2%80%93Howe_generational_theory
In some ways, I'm a believer in the "80 year cycle, theory". But to me, it's a much simpler cause. 80 years is going to be roughly four generations removed from whatever the last chaos was (in this case, Hitler and Fascism and the Holocaust).
The generation that lived through it is long dead. They taught their children (My parents) to never forget. They in turn taught their children (Me...Gex X) to still remember what was fought for. And then the current generation (my kids if I had any) have a far less fundamental grasp on that history. We're so far removed from that event that it's been forgotten just long enough that it all makes an appearance again for the very same reasons. Because it's an easy trap to fall into; blaming someone else for your problems.
All this has happened before and it will happen again. It's as simple as "those who forget the past are doomed to repeat it".
Why did the first notes from The Lion King just burst into my head?