Lol
Does anyone hate people adding GM to their names?

If they are truly GM, then no. In fact, it may help prevent absurd threads such as one spawned about yesterday, titled 'i beat magnus carlsen', where an impostor with username 'magnus carlsen' or something was defeated due to a very silly opening blunder, which no chess master would ever fall into.
Of course, if they are not GM (or IM or FM for that matter), it doesn't make any sense. Adding that tittle will not make them magically play better chess.

Sometimes I also see people who have the chess scores they wish they had next to their names. Like, they'll just stick 2547 or some other number in the high 2,000s after their name, as in pmboris_johnson2578, probably hoping you'll see it and think it's their score. I mean, maybe it's just a random number they like, but I see it a lot. And if that's what it is. That is hella embarrassing.
Why this Hate on me?