About a year ago, I was asked, "Why do you teach calligraphy? Doesn't that saturate the market and in turn creates more competitors?" Surprisingly, in a heartbeat, I had an answer. "It doesn't matter how many people hear what I teach. In the end, those who really want to learn will learn, with or without me." Don't get me wrong on that one--I didn't mean that to come across arrogantly. It's the truth and let me help you understand it a little bit more.
Determination makes it or breaks it
Down the road, those who tried the craft for the knack of it will trail off and lose interest. They will move on and find other things to try. There's nothing wrong with that; some people need to try something to know it's not for them. The others would give up, only because it wasn't as easy as they thought it would be. Most of us want minimum effort with maximum impact, very similar on how little work we want to put in in exchange for a big paycheck.
The small percentage of those who really want it, on the other hand, will practice religiously. Regardless of whether they have attended a class or not, they will find a way. They will have the determination. They will make time and devote it to learning and improving their hands at this. No workshops available? They self study. They don't make excuses and put their Google and stalking skills to use. Sure there were a lot more frustrations when you don't understand your nib, but that's the point: nothing can stop someone from learning something they really want to learn.
You are constantly evolving
As a teacher, you don't actually create competitors; it is one's duty to strive for improvement. Don't get stuck with being a 4 on a scale of 1 to 10. As a 4, you teach the 1s, 2s and 3s. You learn from the 5s and up. While it's true the that the 1, 2, 3 people are gonna move up to 4 eventually, so should you. Each one of us, whether in an artistic point of view or in real life, must evolve. As an artist, we try different media, styles, colors, or up the level of intricacy and difficulty of our work. We should always challenge ourselves. Don't challenge yourself to be as good as someone else. Challenge yourself to produce something better than YOU did last week.
Sure, there will be those who will copy your style, learn it and try to execute it as well as you do. But if you constantly strive for improvement, you'll have a different, much more advanced style than what that person has been trying to copy from you.
Lastly, teaching what you know is like how the ball of life rolls. You learn, you help others learn. Then you learn some more.