Why does no one wave anymore?

It used to be when two biker ped each other, each one would wave at the other. I ride a Harley and an R1. When i am riding my Harley, only Harley riders wave and thats only sometimes. Sportbikers don't. When I am riding my R1, only Sportbikers wave. Why is this? Can't we all just get along. We are all riders. I do live in Los Angeles so that might have some bearing on why people don't wave.