I am a very very lazy person. I like to pride myself on being in the running with Lebowski. And to me hate takes way way to much energy. Having even the simple idea of killing has to take some effort. Kind of seems like he just set out on a life not worth living IMO
Also if you’re wondering why any person turned out the way they are, looking at their childhood explains a lot. Hitler, in this case, had a violently abusive father and IIRC a few of his siblings died (I think from unrelated causes?) when he was a child.