Agreed. Basically, intelligence doesn't transfer from one task to another in a straightforward manner, unfortunately. More gravely, people can find ways to self-censor that are very powerful and very unfortunate (i.e. fooling yourself).
Also, I don't really like to portray people as evil. That tends to dehumanize them and try to separate them into something entirely different, and something distant. Much has been said about this post-WWII, and I agree. Those are people like us, just from a different psycho-social background, which could have been our own; and there is always the possibility of change, if not from leaders from followers. To me the greatest danger of claiming evil is when you stop (or try to get people to stop) thinking there; when you try to find the exact source of harm and carefully explain your reasoning, that's less bad. I didn't know what else to write instead...
Racism, ironically, doesn't discriminate. Anyone can be racist, even otherwise "intelligent" people. I agree that racism precludes my idea of intelligence, but there are plenty of conventionally intelligent people with some really stupid beliefs across the spectrum.
Second, evil can self-destruct, but it can also reign for millennia.
Both thoughts are terrifying.