I don't know anyone like that. But I don't do group rides. If I did, and there was somebody that loud and obnoxious, I'd find a different group or stop doing group rides.
You know there's actually a lot more to riding a bike than going fast. Even for racing. I remember this fat guy passing me going down a hill, then slowing almost to a stop to go through some switchbacks because he couldn't corner on the bike. Skill trumps strength any day. Plus there's rolling around on a nice day, enjoying the wind on your face and the scenery, feeling the burn, challenging yourself on a big hill, and spending most of the day outdoors. Cycling can actually be really enjoyable.