I think that’s an oversimplification that we should avoid. Evil can exist in any person. I think most evil (at least on a larger/societal scale) is actually caused or enabled by people who truly believe their cause to be morally right, as well as people who are just plain ignorant/stupid. Germans under the nazis were certainly capable of empathy, but they were convinced it was the Jews who were evil and that they themselves were truly superior. I think the average Trump voter was capable of empathy, but they just didn’t see the reality of who he was because they were ignorant, either willfully or otherwise

Edit: I also think a major cause of evil is dehumanizing/“othering” certain people. I’m sure many in the KKK are capable of empathy, but they’ve successfully dehumanized other races to the point that they don’t see anything wrong with brutally killing them