Sam1911
Moderator Emeritus
I guess people who already know everything probably won't benefit from taking a class. Heck, maybe they should take up teaching them!
Actually...the best teachers spend a lot of time taking more instruction, training, and spend time in defensive shooting Study Groups and Conferences.
The more you learn, the more you realize you have left to learn. They tend to consider all who study these things to be simply students on the path to greater understanding. Some farther ahead, and some just starting out, but students, all.
The less folks know, the more convinced they are that they've got a handle on it.