Re: Why do teachers stop learning?
One Word: Status
People like being the guy that "knows". It's great to stand up there and have everybody all wide eyed and adoring. If you can create some sense of yourself as posessed of "special knowledge" to which they may aspire at some later time you can really go to town.
But it's very difficult to maintain that lofty position but train at the same time. If you try new things your students might actually see that there are things you don't know or that there are people out there that are better than you are. It's difficult to get your students believing that you are the Big Kahuna if you go off and look to others for training. That would mean you are only a medium or even small Kahuna.
I remember reading a comment that Fredrick Lovret Sensei (controversial Aikijujutsu instructor) made. He said that if a student asked a question, the teacher had to have an answer, even if he made one up. Now that is a perfect example of someone who cannot afford to be seen learning anything from anyone else because it would diminish his status. He has to spend all his time making sure that his students are doing exectly what he is teaching, exactly how he is teaching it. If he can do that then he automaticaly stays at the top of the pack. "Right" is defined as his way, and he will always be able to do his way better than anyone else.