There are fewer wars than there used to be. The percentage of the population for whom violence is not a regular part of daily life is much greater than it has been for most of history. OTOH, when violence does happen, the weapons available are far greater, able to cause far more death and destruction, than in the past.
All wars are economic in nature. Scarce resources and growth are at odds. Some societies have been peaceful and found balance in the resource usage. They tend to get overran one way or another.
But seriously, it seems that conflict emerges because there exists difference of opinion or conflicting desire. Violence seems to be escalation of those conflicting desires. Maybe the answer is “war exists when we fail to de-escalate conflict”
When foreign armies hire mercenary groups to invade your homes so that they can maintain plausible deniability for what they know is an illegal and immoral act of war, I don't think there's any debate among non-psychopathic people.
No. What is dangerous is refusing to recognize that bad people exist and do bad things. What is dangerous is calling into question people's right to defend themselves.
Nobody can stop you from believing that, e.g., Ukraine should just capitulate to Russia and give up its freedom. But don't pretend for a second that such a belief holds the moral high ground.
On one of the levels without ww2 and the cold war afterwards — there would never be the Internet and modern computers as we know them [1]
On a philosophical level — as long as there is a dualism, there is a constant battle and interplay between the sides. So war in one form or another is as inevitable as peace.
In a sense the whole life itself is a constant battle between good and evil, chaos and order, entropy and information [2]
On the surface — scarced resources, justice, religions are just silly stories that people create for themselves to sugarcoat and rationalize those (or other) deeply embeded into the reality drivers.
This was ultimately the reason given for the ancient Trojan war. That Zeus was upset that there were so many people in the world. That is in fact the true meaning of Odysseus’ name. the “child of anger”, given by his uncle for this very reason “too many people in the world!”