Being new to boating, i kinda like the wave. I usually reserve it for other sailors or to reciprocate others who wave. Seems the PWC crowd is too busy zipping around to wave. I agree with the OP because sometimes i just want to be left alone and enjoy my time on the water.
I have been riding motorcycles for years and i admit i have grown weary of having to wave to every single bike that passes by. Just because we both are on two wheels, doesn't make us buddies. Anyone wave to every car that goes by driving down the road? Not every person on the water is a social butterfly, some of us are out there to get away from the throngs of people we are surrounded by on land. Don't take it personally, it's just the way we are.