The Biggest Mistake Writers Make When Crafting Villains

I love villains. Well, no. I don't. I don't love villains. Not in real life, anyway. I've known a few. Interviewed my share, back when I was a newspaper reporter. I don't enjoy hanging out with villains in the real world. But as a novelist, I love writing them.
You will notice I did not say I love writing ABOUT them. I said I love WRITING them. That's because the number one mistake I see novice writers make when writing villains is in writing about villains instead.
So, what's the difference?
The difference lies in the emotional truths captured by the point of view.
To write about a villain, a writer must take a point of view other than the villain's, even if they don't realize it. Many newer writers will still retain their own (or society's) point of view in writing about the villain, without realizing it. They might even do this in the first person, when it is supposed to be from the villain's point of view.
Let me give you an example of what I mean. Let's say the villain is a white supremacist terrorist, like the ones in my forthcoming novel, HOLLOW BEASTS. A novice writer might write about such characters by saying something like "he was proud of his racist views." The problem with this is that the villain sees his views differently. The writer and general society think he's a racist and a terrorist; he doesn't. He thinks he's a hero, a patriot, a savior, a protector of what's good, a warrior for Jesus. Etc.
In his book THE WRITER'S JOURNEY, Christopher Vogler famously said, "Villains are the heroes of their own stories." A white supremacist terrorist, in his mind, isn't a racist, because it isn't even in his emotional vocabulary to accept racism exists. To himself, he's a pragmatist, a truth-teller, a plain-speaker. He's saving his people from inferior criminal animals. He's heroic, to himself.
Writing villains well takes loads of toxic empathy, something it is best to avoid in real life unless you want to end up as one of those women who only dates prisoners. It takes looking at the world as the villain would, and allowing him to speak. Do this, and your villains will be truly terrifying. Don't do it, and your villains will be cartoonish and uninteresting.