True enough... colective<individual. You're right, there are many things that right now we can't solve on other areas, but war isn't one of them. Yet honestly, you know how easy it is to influence individuals in a collective. I'm not going to war, not now, not ever, I would only go to protect my family and loved ones... yet there are many people that are convinced otherwise, they're convinced that the military pays well, that they're mostly exercises and they're never in real danger, that they will live comfortable, that they will be granted residence, etc...
Let's face it, if you're going to die of hunger you might as well die on the battlefield, no? But in reality that's just conditioning, there is no real necessity behind it; nowadays money can be made with a lot less danger overall and when individuals realize that, then poof, just like you said: no more wars!