I forgot who said it, but it went like this: "If people recognise the banality of war, there will be no more wars." Of course its not that simple, but we, I suppose especially us techie boys (us because I am one), think that an M1 Abrams tank, a F-15 airplane or a Sig Sauer rifle are, well, cool. We also think uniforms look good. And we dream of being heroes, especially when we are young. It is, of course, nonsense.…
It's not that wars are seen as heroic, or religious differences and other such BS.
A lot of modern wars can be explained as the results of colonialism (either traditional or in its current covert form). Larger countries have interests in exploiting less powerful countries, to get control of trade areas, cheap oil and labor, etc. Of course they say the bring "democracy" etc, even when they leave chaos and hell on their way out (plus some profitable contracts for them).
Before the 60s the did it directly, literally enslaving 7/10 of the world in their "colonies". After that they do it by proxy (e.g. by drawing borders in such a way that establish countries and "nations" that will fight between them so that they can more easily control the area, install lackeys in power, etc.