He does it because, amongst other things, he has a tolerance problem. He has very little tolerance for other people's opinions, personalities, ideas, wants, needs, etc. He constantly bitches about the other HMs. He is sneaky, spiteful & controlling. He is basically a nasty, toxic person. He just can't/won't put himself in someone else's shoes. He is the alpha male bully in the schoolyard, and the other boys look up to him and/or fear him. He doesn't like to be challenged. I've also noticed he never apologises when he has arguments with people. Most adults settle things with mutual apologies.
I'm glad he is not in my family.