I wouldn't call people doing dumb things stupid. We've all done stupid things, and probably will do so again, that's human nature. The thing I've taken from this thread so far is that a father/son combo went out and started doing some taxi practice on the "off-duty" runway without telling the guy who was in the air what they were doing. I've found that the most important thing when others are flying is communication. Just walking up to a guy flying and asking in a calm, non distracting manor, "Hey, do you mind if I do .........." can solve a lot of these problems. When you do this, they guy flying knows what your doing, and if he agrees, accepts the risks (if any) that the situation presents. Also, you should never be on the runway durring flight ops for any extended period of time, either the active or off-duty runway. If you are going to enter this area you need to announce this so everyone knows you are there, and also let them know when you are clear.