Merc probably suffered a tragic event, maybe his wife died in 9/11, maybe one of his kids got killed RIGHT INFRONT OF HIM, I don’t know but I think Merc is living in a fantasy world.

Merc lives in a world here he thinks he is a succesful lawyer and acts as such, acting superior on a internet forum and thinking people truely care. He plays incit all day probably because the people there remind of his family/get his mind off that tragic event. He re-acts so strongly to people who disagree with him, because to him they are disagreeing with his world thus he must use as little brain power as possible and come up with a name to call some one if they hurt his feelings.

TL;DR Merc lives in a fantasy world here he thinks people care, and should probably seek help in a mental hospital.