"How do you solve long-running civil war?"
"Murder all the grandmothers."
His point being that they were (a) the only ones who survived into old age (everyone else getting murdered) & (b) were thereby the ones educating a new generation in the hatreds of the old.
He was only half-joking.
But it really made me think about, as you say, just how long it takes for institutions to be built in a society. Which is order-of-"the time it takes for mindsets to change (usually via death) or new generations to rise into power (~40 years)".
I'd never really thought about it that way before.
Or put another way, it's easy to push systems towards increasing entropy, but hard to push them in the opposite direction.
That's part of why terrorism (of any persuasion) often chooses targets of symbolic value, like social, political, and economic hubs. They are trying to push the target social system toward entropy.
100 years is nothing in the grand scheme of things, but unfortunately, it can all be undone quite quickly. When older generations sacrifice short term gains for long term security is when progress can happen. Unfortunately, I don’t see much appetite for that where I’m from (the US), and once a sufficient number of people choose to take more from the system than they give, it will start decaying.