A lot of people who find the holocaust horrible today, would have participated at the time. We're all a product of our social environment.
I'm 73. When I was young, it would have been unthinkable that homosexual people ( the polite expression at the time ) could marry or adopt, or even hold a public position. You could hear the words "nigger" or "coon" in sitcoms, admittedly spoken by lowlife characters. But to say "fuck" on the air was unthinkable. Now you hear fuck all the time, but the racial slurs are absolutely barred, even in jest. All good stuff, but they are just examples of fundamental culture changes that are all good.
But the people haven't changed, it's the culture that's changed. Take people born today, transport them back to the Nazi era, and they would do the same.
Nazi Germany grew out of desperate times. People act differently under pressure. They tend to pick on anyone who stands out as different, and blame them for their problems. It's still happening in India, Bangladesh, Burma, China, and not too long ago in Northern Ireland. Those are just examples, not the whole picture.
The common factor is human nature, it hasn't gone away, and it's not just Nazis on Jews.