By sociopathic behavior I meat mainly the noise. There's 0 need for most bikes to be as loud as they are. Bikers install loud exhausts because they like it and they don't care about anyone else.

And it's 100% a hobby for many many people. I'm sure it varies by region but were I live there's plenty of mountain roads that fill up with motorbikes every weekend. Stats confirm it, most of motorbike accidents happen during the weekend. Those people are not traveling from point A to point B. They go on weekend rides. And those "fun" rides usually involve excessive speeds and noise. Maybe it's different where you live but this is what I see on roads around me.