I think what OP is asking is not about why people like that exist, but how they become one like that. Where it all started.. Actually, It's all about the imagine, which people created themselves and that spreads like a virus. People tent to be more respectful when they are new, since they were learning, and connection is what made (make) good players the best. We all know it. But, once people get used to a game and start to develop their own playstyle, they become more aggressive... and question; why can't you do this or that, it's obvious!!. Some people get even deeper with elitist mentality. It's all natural. Only intelligent players treat others nicely, because they value people.