Reasons I don't wave unless I'm waved to first:
1. I'm wearing a full face on a cruiser so I can tuck past 16 wheelers on the highway (I'm so hard core I don't have a windshield!!) so I don't get blown off the road
2. You probably think I'm on a chinese bike
3. You probably have no respect for me or my bike even though we're both riders, but your girl on the back still waves to me

4. If you're on a GW or HD and you wave first, I'll wave back I'm cool like that
I'll even wave to a guy on a scooter if he waves.. I have respect for all riders..