Do you have to be an Economist to teach Economics? Do you need to write a novel to teach English? Do you need to be the President to comment on the kind job he is doing? You do not have to have a job in that field to have an opinion.
The answer in short is NO. I have met great athletes who did not know the first thing about coaching. I have also seen mediocre athletes. Someone with no first- hand experience in the sport has become a great coach.
Just because you know how to fight, does not mean you know self defense or more importantly how to teach someone how to protect themselves. The first thing you learn as an instructor is you are not your students.
It's easy to teach a room full of testosterone filled hard-chargers how to protect themselves. They are already three quarters of the way there! The real challenge is teaching people who really do not want to hurt someone to systematically protect themselves against attack.
Self defense is not you going out looking for a fight it is you learning to defend yourself against an attack. You might not even have to use it, but it is a good idea to have the knowledge to know how to if you are ever find yourself in that kind of situation.
You never know what could happen if you work late and you're on your way home or even going for your daily run. What is going to happen or who is out and about.
I have trained excellent instructors that have more to their credit than I do. Who got it.
Every athlete, instructor and coach has asked this question at one time or another: "How do I pour decades of training and experience into a person in a matter of months?"
We have all come to the realistic conclusion...I can't. But I do not have to. Based on the facts and my knowledge I am able to provide the highest percentage solutions for some of the most difficult and down right dangerous situations. Good instructors can recognize tactics and principles and learn to apply them to any situation.
You can run into issues when we decide to deviate from tactics not technique. Really at the end of the day, the technique is secondary to tactics. Once you have a handle on this you will have the ability to teach anyone, anything.