How do you reliably prevent a clever psychopath who's set their mind to it from gaining power?
I think the answer could arise from a widely growing understanding of
a) the methods of mass manipulation. Without manipulation, or outright mass hypnosis, no dictator is possible;
b) the whole structure of power, and the fact that there are numerous barriers to filter out all non-psychopaths along the way to the top, with multiple checkpoints where an ever increasing degree of corruption and depravity must be demonstrated to the controllers.
But even a) alone should be sufficient.
"We". "War is in our genes".
Start with "me". Do I need war? Do I want war?
Do I have something that differentiates me from a simian?
To bear a reasoning mind, and have a heart that is capable of love, and still to appeal to the animal foundation is a total betrayal of everything that makes you not just yet another animal.
Idealism has been carving into reality nonetheless.
Our current standards of living are straight out of platonic Eidos, compared to those of our cave-dwelling predecessors.
Computers are also a perfect example of materialized ideals. Airplanes, Internet, space exploration, you name it.
Why should that stop at war for any reason other than someone having a deep vested interest in it?