Generational dynamics / Fourth Turning tells us that wars start because the older generation that survived the last crisis war die off leaving a younger generation that thinks it can fight a war. Here's a conversation on Reddit. I guess they get it:
She's one of the last members of "the generation of warning voices". People that lived through WW2, have seen its horrors and later always remembered it.
These people were everywhere in the societies on both sides of the iron curtain and whenever the west/east ran into a problem, in the end they talked about it before they pushed a button or started another world war because in the back of their heads they heard these warning voices.
Sadly these voices have become extinct and now look where we are.
and
Right, the last few still living have already been forgotten, their warning memories lost to most.
People forget details and history repeats itself. Most see WWII as some distant, forgotten event that couldn't possibly happen again, and as you said...look where we are now.
War begins when the older generation that survived the previous crises war dies off, leaving a younger generation that believes it is capable of fighting a war, according to generational dynamics and the Fourth Turning. Here is a Reddit discussion. I guess they understand.