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
Dont forget about the insane shit the Japanese did too. This dives into the reasons they did Mark Felton documentary: WW2 Japanese Military Brutality