Most hours gamed are by kids, of course they're gonna be nasty, have you ever seen an unsupervised kid without threat of physical violence for being shitty to other kids?
The fact that people care about an insult or attack in a comment section of a random site they read about a game is what surprises me. What lives some people must live for this to be something that even registers as an annoyance.
I don't think most of these types of comments come from kids. "Entitled gamer culture" seems to be similar to any kind of culture around fandom, escapism, entertainment and sports. Some people just love to obsess about things and take their opinions super seriously, especially if they don't know what they are talking about.
I actually do think the reason why gamers tend to be nastier as a group comes from them having a large group of children and teenagers. The vast majority of a group are lurkers, so you only need a small percentage of vocal jerks to make it worse. I bet most of the jerks and trolls in the gaming world probably skew younger vs. total gamer population.
The fact that people care about an insult or attack in a comment section of a random site they read about a game is what surprises me. What lives some people must live for this to be something that even registers as an annoyance.