My argument is that from a utilitarian perspective, people with good intentions doing [bad, evil, unethical, whatever] cause much more human suffering and misery than those people whose intent is evil and yet they so often are given a pass on their actions.
And then either way, you could make this argument like: "why did person x choose to be evil where as person y chose to be good." That seems almost more arbitrary an likely to be biological from a detached perspective. I'd much rather judge people on their ability to deeply introspect and evaluate the world and come to good conclusions.
Between born psychopaths who seemingly can't even empathize with current or future victims https://www.psychologytoday.com/us/blog/thinking-about-kids/..., and criminal rational choice theory http://criminal-justice.iresearchnet.com/criminology/theorie... which posits that even most of a criminal's willful acts are rational given their circumstance and motivations, I don't think there's a tremendous amount of room left for "true evil".
I can't help wondering if history will look back on most of what we see today as "willful evils", instead as "misunderstood tragedies"... see for example https://en.wikipedia.org/wiki/Charles_Whitman whose tower sniping was initiated by... a brain tumor.
The truest evil IMHO is that committed by people who believe they are doing good (but perhaps are "making the tough decision"): see the Nazis.