I know a dude like that. My normal group brought two new people along for the hard raid. One guy is great (person and player). His friend however is one raging ape. When he dies there's always excuses. When one of us dies he goes absolutely ham on them. People try to talk to him as little as possible. It causes so much tension and uneasiness in the fireteam that it's not fun. We'll be at it for hours. He'll end up rage quitting. We get someone new in and we get it in 3 goes. This has happened twice now. I'm removing myself from the equation even though the ragers friend is one of the best players I've met.