National-socialism was a collectivist ideology. It was grouping people according to a hierarchy of "races", in other words judging individuals according to their ancestry. It was fundamentally horrible not because of its form of collectivism, but because it was both collectivistic and totalitarian.
Human action is driven by ideas and personal choices, not by collective biological origins or urges, nor by "feeding", nor by "physical training."
If you want a deeper, intellectual, practical understanding of what made Nazi Germany possible read "The Ominous Parallels" (1982)  or an extract titled "The Cause of Hitler's Germany" .
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