Who has been thrown fantastically and gotten up and said "show me how to do that" with a huge grin on their face? I have, many a time.
If I was the one being asked and I knew that I was going to face this person who was asking in competition at some point in the future...I'm not sure I could bring myself to show them something that they could use to defeat me.
There you go. My ego to protect my chances in a competition. So much for letting my cup floweth over and give all I know to you, free of charge because 'tis a wonderful thing we are studying here.
Just a thought...perhaps even a sobering thought...and probably more a reflection on my lack of character than anything else <sigh>