I agree with genetics engineering as the answer.
Our DNA has greed, power tripping, paranoia etc. hard coded somewhere. The correct combinations might stop all wars.
But all in all, wouldn't it make humanity dull and unsatisfied? I wonder.
I'd argue that humanity is humanity and we wouldn't remove its complex emotions, philosophical wonders and existential dread.
Desire for more out of life, search of meaning, etc.
Unless we go all the way and engineer ever flowing euphoria from birth to death, for everyone. But then, what's even the point?
I think if we had someone with charisma start a suicide cult, things would generally improve... I'm Trevor to make a Joe gRogan joke, but I'm actually at least half-serious