It's probably some form of evolved survival technique. Too often applying lessons from the past to a current issue is in direct conflict with your own preconceived notions of how things should be because of personal experience, religious beliefs, etc. If that conflict is extreme, the brain goes into rationalization mode to ensure the stresses of that conflict don't put you into neuron gridlock. That condition can be hazardous to one's health especially in our original animal selves where too much confused contemplation would get one eaten by a saber-tooth tiger.

A keen and unbiased view of history is essential for humans to evolve socially. You are spot on when you apply lessons from the past to the futility of war and violence toward one another. However, just be sure that you don't conveniently omit parts of history that don't support your hypothesis. Of course Vietnam had very little good come of it. You'd be hard-pressed to find any positives. However, there were certainly good things that came from WWII although I'd argue the overall effect was about null given that it empowered the Soviets. Let's also never forget the "butterfly effect". Every action, no matter how despicable it may appear, sets us on some new course and a terrible death in one century could lead to an amazing circumstance years later.

When I've argued with people on here about the terrible effects of religion and faith mingling with powerful nations, I cannot in all honesty neglect to mention the horrors that have been committed by governments that proclaimed themselves devoid of religion. My argument is still compelling even if I make that acknowledgment because the number of wars, atrocities, and acts of aggression done in the name of God has far exceeded the damage done by secular societies (especially if one looks at the individual makeup of actual people doing the atrocities. Even if their government calls themselves non-religious, the citizens are far from that). Still, at the end of it all, there is no right answer when you're dealing with human behavior. There are too many variables that are impossible to quantify.

You probably didn't deserve such nit-picking because you correctly identified your post as a rant. It was only the irony of your total history that got me involved and gave me a chance to rant as well.

Art