It's not hard to never get in trouble. If you're a self admitted rager, you're 95% of the way there. It's frustrating when you lose, it's a bummer when you get bad teammates, but it is never justified to treat others badly. Remember, we're all playing this game to have fun, win or lose.
Instead of getting angry at your teammates when they are struggling, try to help them out, either by encouraging advice or helping them out personally. Telling them they're bad, noob, feed, terrible, whatever else you might say, will never help them improve - in fact, is usually discourages them from trying and increases the chance they're going to leave the game or come out of it just frustrated and in a terrible mood.
Being nice isn't being weak. Being supportive and helping is what leaders do.