Again, this is not a proper discussion without bringing up narcissists / psychopaths.
At the heart of it, a psychopath is a coward. They don't want to do the thing, not because they would feel bad about it (they don't) it is too hard, too messy and too much trouble. Further, they don't get any enjoyment from it.
A normal person may talk about killing someone because they are a threat. A psychopath thinks about it only in terms of which path has the least problems. The normal person will kill in the heat of passion. A psychopath has no passion. They will kill someone just like we would throw out a broken tool.
So, the most important aspect is "duper's delight". It is the highest drive for a narcissist. Getting people to do evil thing to other people is their fun. And they will plan it out every waking moment. They will manipulate all people within their influence.
Would you get your platoon killed if you were promised a medal?
Well, there are several stories of that in Nam.
Further, following orders is easy. Being a brown shirt and stating, "All jews aren't bad" is similar to committing suicide. And, every brown shirt knows that those lying, good for nothing, cheating, lower than dogs jews don't deserve to live.
So, you really have to work on yourself to get out of this one. You cannot ask a brown shirt to not follow orders, to stand against them. They have already been indoctrinated fully. Those who weren't indoctrinated, left when they saw the writing on the wall.
What we need to do now is voice our opinions. We need to let people know that there is more than one of them that thinks these actions are wrong.
I disagree on psychopaths. Nothing prevents them from enjoying killing or murder, many psychopaths do enjoy it. Psychopathic development might be linked to enjoyment of torture and killing in youth. Narcissism is related to not having love for others and a false love infatuation with self to cover up their lack of self-love, not directly related to experience joy from the pain of others although that can be the case. Narcissists would be more the ones who are "dead" inside, no? So I think your definitions are a bit confusing the way you use them. But I get what you're driving at ;)
My definitions come from dealing with and healing from narcissists.
And, unfortunately, the media has done its best to change the definition of psychopath to Norman Bates and silence of the lambs. I would not call these people narcissists / psychopaths.
The defining characteristic is a lack of warm empathy.
So, they are not "dead" inside. They have feelings, for themselves. Other people, they have as much feeling for as one would their computer.