So you start out with a space to teach in. By the time you get enough students to actually cover the costs of running that place, you have already outgrown that first training dojo.
So now you need a bigger place. Which is going to cost more, so you will need more students.
On average it takes about 10 years to actually have and maintain a solid base of 30 students. As an example lets say that means during those first 10 years you might have 100 potential students come through your doors, but only about 30 of them will stay long term.
If you are charging $100 a month thats $3,000 a month you are bringing in. $3,000 a month is not a lot of money considsring that at that point, you will probably need to move into a bigger space.
That’s just the first 10 years. The first 3–5 years you will be lucky to get 10–15 students, for $1,000 to $1,500 a month. During that time you will have a small dojo, and probably be fronting much of the costs yourself.
Then you have to consider that people move, or change jobs, or have a baby, or grow up and go to college, or get involved with video games and cars and girls and tons of school activites. My biggest competition? Video games.
Then most kids and adults come to find out that studying martial arts is a lot of work (yes moving the body somehow equates to work these days) and a commitment of time. Progressing and sticking around to get a blackbelt or maybe actually learn a particular art or style can lose its appeal, despite all of the benifits of training in a martial art.
Not to say it cannot be done, but If you are actually teaching a martial art (as opposed to running an after school day care program disguised as a martial art), and you take all of this into consideration, you can probably forget about seeing any kind of a profit, especially in those first 10 years. You will be very lucky just to break even.