I believe that rude old people were once rude young people but they do it louder because they're a bit mutton-jeff and they do it in public because they're not hidden away at work any more.
I don't think personalities change very much with advancing years. If they do, I'm not looking forward to what some of my middle-aged aquaintances are going to become. I know one or two pretty obnoxious 40 and 50 year olds who will make foul 80 year olds.
