Most stories need an antagonist of some sort, and for a lot of genres, that means a villain; someone who, whether they see it that way or not (realistic ones usually don’t), is doing something that is indisputably wrong.
People who intentionally choose wrong for its own sake don’t really exist outside of cheesy fiction that’s not meant to be taken seriously, but that doesn’t mean that villains who know what they are doing is wrong and don’t care don’t exist. And on the more sympathetic side would be anti-villains who regret their actions but consider them necessary.
Still, people whose understanding of right and wrong is itself flawed are a lot more common in real life than villains who know that they’re villains. This tends to be more interesting than the other options anyway because it allows the villain to have more depth and individuality while still clearly being the villain. Of course, some morally grey stories, and some real life conflicts, have had this type on both sides.
At the other extreme opposite the card-carrying villains, though, is something else that’s far more common in fiction than in real life; life-or-death conflicts where everyone involved has good intentions, with little malice or selfishness on either side. Ideological conflicts often become this in fiction, but notably they usually have to resort to a true villain if they bother to explain how the conflict started/escalated in the first place.