HOW DO YOU DEAL WITH THIS?

I'm tired of having to kiss up to trolls and coddle their insecure childlike egos and personalities because they threaten to feed. Here's what happened:

• I play a ranked game, and we're winning pretty easily early on; bot has the majority of our kills and our adc is really fed

• The bot lane support (duo'd with the adc) said something along the lines of "Your welcome for the carry :)" which was fine and I gave a polite "Thx bae" in return. Whether this was true or not, the bot lane credited their success to the fact that they were smurfs. They were playing fine, so I didn't really care.

• Then, one of my teammates (not putting his lane or name to prevent witch hunting) replied something like "Oh, you're not carrying, blah blah blah, you're not even that good," though honestly, he wasn't doing that great himself.

• Bot lane (not really condoning this but it wasn't that terrible of an offense) was like "Get carried, scrub" or some confident junk like that. Again, it's nothing to cry or care about.

• Then my angry teammate proceeds to say stuff like "Well, if you're winning so hard, you obviously don't need me," and refusing to group saying "Oh, you can win easily without me, just ask (misc. bot laner name)"

• He wanders off on his own to other lanes, split pushing but not really split pushing and dying a lot. And here's the thing that he said that enraged me the most: "Don't f*** with me, remember. This game's fate is in my hands." (Cuz he threatened to afk)

• We won that game, but not without having to endure an extra 20 minutes of a 4v5 with the angry teammate constantly spouting junk like "Some people don't deserve to win," and "Honestly, I don't even care about this match anymore. You guys shouldn't win."

HOW DO YOU DEAL WITH THESE PEOPLE? I really tried to be nice to him, and tried to get him to mute (misc. bot laner name), but he seemed to enjoy his newfound power and my begs actually seemed to be STRENGTHENING his resolve to leave and troll us. But on the other hand, if you ignore him and/or scold him, they're just going to do whatever they're going to do sooner, thus ensuring that you are most definitely going to lose. We won that game, but I'm posting this because I know the same situation has happened to other people and they've lost because of it (we almost did).