I know at least some journals of prominent party members have been uncovered, so I was wondering if any kind of consensus can be reached on their emotional state/the real reasons behind their actions?

I am wondering, I guess emotionally speaking, why Hitler and other prominent Nazi leaders did the various atrocities they are attributed to them. Did Hitler enjoy killing people, or did he profess remorse in private settings where we can assume he was speaking his mind? Was it just a personal play for power? Did he honestly believe all of his actions were just/ethical/for the greater good?

When they sentenced the retarded and disabled, the Jews, entire portions of civilian populations, to death, did they think it was somehow for the best? Did they revel in their power over others? Or was there no emotion at all, the atrocities were just a net benefit?