When it comes down to it, nobody really thinks they’re a villain. Even the most evil character a storyteller could dream up isn’t walking around going, “Isn’t it wonderful how evil I am?” No, they legitimately believe they’re doing the right thing, even if anyone with a working brain could see otherwise. The most cartoonish villain simply thinks the world would be a better place with everyone else subjugated under his oppressive rule.
But that means that every protagonist is someone’s villain, and not even necessarily the dictatorial monsters. A lot of so-called “heroes” are incompetent to the point of inexcusable negligence, or their solipsism threatens to smother their surroundings until it becomes a self-fulfilling prophecy, or they’re just a dick for no reason and it’s weird no one talks about it.
As a result, when user youre_a_lizard_harry asked r/AskReddit, “Which character is not technically a villain but is actually worse?” Reddit had a lot of long-simmering grievances toward fictional heroes to air.