Have you ever watched the "Big Bang Theory" TV show? There's a reason a character like Sheldon is portrayed in the show: Elements of that character are found in a number of disciplines, including programming. What I am saying is, there are people who are utterly rude and inconsiderate and don't actually know it. They somehow failed to develop human qualities about them. They exist and are very real. I worked with a guy who would wear a badge reading "Asshole <his name>" for years. People left him alone. He was very nice, but playing that role got him peace and quiet.

I would venture to guess that most online assholes are socially dysfunctional people.