Think of all the wars in our history - all of them. From the world at war in 1914 to the petty little royal wars of this kingdom or that in 963, this tribe or that in BCE360, this clan or that in BCE26,000. All the wars, all the violence, all the death and destruction - for why? And I ask this from an evolutionary perspective.
Survival of the fittest, I suppose. Via technology - I'd argue technology was created and ever honed because of war and violence, up to and including this day. And what a mighty world we've built with this technology.
With so much loss. Think of all the dead, and not just the troopers, soldiers, warriors, etc, but the women and children, the old folks brutally chopped down. So much death and loss, but so much gained.
We're Gods now, super heroes bestride the World. But terrible, petty, vengeful Gods, prone to violence and random acts of killing.