I agree, depends on the person.
Sometimes it gets like that between brands of bikes and people, too......
I see a bike headed my direction, I always wave, regardless. Sometimes they don't wave back, but it's okay.....it's what I wanted to do, and that was to extend a greeting to them. It's nice to get it back and sometimes that wave is what will make their day, you just don't know, yep, even the "bad" ones......