Rants without evidence mean nothing. I'm very new here and I've found nothing but encouragement.
Bad manners

This is war baby, you gotta have a thick skin
But seriously, don't let the negativity get to you, don't let strangers push your emotional buttons.

meh just block, report if they actually did make death threats, and turn off the chat. Things like that just make me laugh.

Yeah, I'm sure you've experienced some bad manners in chess, but I doubt it eclipses some of those other sports (if you've actually played them). It has less to do with chess around here and more with the anonymity of the internet. Just block them and move on. If they make a direct threat, then report to Chess.com support and they're pretty quick about responding.

Stay away from League of Legends, fps games, most if not all multiplayers games, comment sections and maybe stay away from the internet in general.

This is war baby, you gotta have a thick skin
But seriously, don't let the negativity get to you, don't let strangers push your emotional buttons.
Sorry, I'm old enough to remember face to face manners. Can you imagine saying some of these things said online, to someone face to face?
The thick skin is acting nobly in the face of defeat... or victory. It is hard enough completing a game, or anything for that matter, with dignity.
And yes, I know that sounds old fashioned. At the end of the day though, it is as true today as it was 100 years ago, when I was born.

Stay away from League of Legends, fps games, most if not all multiplayers games, comment sections and maybe stay away from the internet in general.
Learn how to behave towards grown-ups.

I have never in my whole life experienced more bad sportsmanship, bad manners, rude manners, and even got deaththreads from all levels of chessplayers, than in this sport.
I have played soccer, Backgammon, Poker, and I ser pretty much in 20% of my game. At least.
I sympathise. Chess attracts the socially inadequate, and Chess.com in particular is mostly colonised by children, so unfortunately this kind of behaviour goes with the territory.
I have never in my whole life experienced more bad sportsmanship, bad manners, rude manners, and even got deaththreads from all levels of chessplayers, than in this sport.
I have played soccer, Backgammon, Poker, and I ser pretty much in 20% of my game. At least.