Doesn't this all just come down to the fact that lambs think eagles are evil and eagles think lambs are tasty?
Who in their right mind wants to send their offsprings to butchery in war? It can only happen if you first create meaning and justify the war (e.g. a clear danger worse than war) if you expect people to follow.
So the real issue here is how easy it is to manipulate humans, to make them act like robots programmed by mainstream media so eager to show us a danger and the difference between "us" and "them".
This does not mean there is no intentionality though. Is it really a coincidence if some weapon manufacturers invest in media companies? Is it a coincidence if the same source of finance feed both sides of a conflict?
Realistically adults don't think about the morality of their actions much at all.
If you're basing this on personal experience then either you or I are atypical because I think of the morality of my actions all the time (and sometimes makes judgement calls which are different to social norms).
Like intelligence, moral IQ is a spectrum that probably most don't consciously think about until a conundrum comes up, but that generally centers around a mean, and spans multiple areas that overlap across cultures and generations and behaviors.
Whereas in our world, we judge each other with our own set of complex rules, and we treat each other based on those rules, rather than just rules of survival. It results in a lot of conflict that has absolutely nothing to do with competing for a mate, finding food, or sheltering. We trick ourselves into believing the complex rules are more real than reality. We think 'evil' is real, when in reality it's an imaginary concept that doesn't exist as a part of nature. There is no such thing as an evil being.
Hell, we think there's an invisible being in the sky that watches our every move and judges us, and based on that belief we kill people. As a species, we're insane.