90% of the time I don't see the people waving at me ...although it's hard to estimate the number of people I DON'T see lol. I usually wave back to those I do see, but sometimes it catches me by surprise and I shy away, looking away from the other driver.
I guess in the eyes of the OP that makes me an "a**hole" and a "douche bag" worthy of receiving the "middle finger", and I should take my "weak sauce" and "get the f*** out".