That is exactly what I do, even when in my car, if I see a person riding a bike, I wave. If they wave back, great, if not.... well then I hope they find a good therapist and work past their issues.
Sometimes, I don't have the breath to yell out "hi", other times I need my hands on the bars so I can't wave, yet others my focus prevents me from nodding my head in acknowledgement, but it is a rare occasion when all three happen simultaneously and then, for the next few minutes, I fell beneath myself but vow to make it up to the next rider I pass!
So, not sure if your comment was sincere or antagonistic, but mine is sincere and if it opens an eye or two, it was worth the time to type this post.