I do a partial wave (hands never leaving the bar or hoods) to everyone - some wave back, some don't - doesn't change my routine, I still wave
I have noticed during my years of riding that mountain bikers seem to be acknowledge the wave more than roadies seem to
who knows why?
as far as being arrogant - the only time I am arrogant with my "roadiness" is when any of my non cycling friends or coworkers make jabs at me for wearing cycling shorts, jerseys, etc...
then my usual response is - go out for a ride with me & then you can make fun of me all you want...