Honestly, I think waving is silly.
It's not like we're all overcoming some life-threatening disease or meeting up for the big game. Neither does anyone wave to every walker, driver, or fellow riders on the bus or train. Is the act of waving to other cyclists the same kind of approval-seeking that makes people say, "Hey mom, look at me!"?
I'm not antisocial, mind you. I'll chat about our bikes or the weather or whatever as we're tooling along. As an example, I got put into contact with a sports physiology clinic because of talking with a stranger during a ride. I'll often try a head nod or just a lift of the finger, or just a "'Mornin'" while we're waiting at a light.
But, really, most of the time, we're just trying to go somewhere. Bikes become plain ol' transportation devices after a while.