It's not a group that's like this, it's a widely distributed human behavior (I'm not quite cynical enough to call it a universal human behavior although some would.)

Sure, but it’s those people who behave that way.

They're not a group in the sense of "an in(out)group." That would require some kind of identity. It's a behavioral tendency in the sense of having a short temper or being gregarious, rather than a belief system or a club.