I live in an area where BMW 3er's and 5er's are as common as Civics and Accords. The majority are driven by women in their 40's. Not to be misogynistic, but maybe it's just that women can't drive?
All kidding aside, I've never seen anyone in a Beemer rage at anyone so I'm not sure what that's about. I do think there is a public perception that the majority of BMW owners are badge whores who bought a BMW because they think it gives them status. Unfortunately, these people give enthusiasts and non-enthusiasts (who just appreciate a great car) a bad name.
I think every brand has jerks. When you compare luxury brands it would only make sense that BMW has the most jerks as they sell the most cars.