I ran a music store with a ton of students. Basically 6 rooms with a huge store and tons of instruments.
I personally found the whole thing to be very frustrating and discouraging.
Most of the students were forced to take lessons by their parents. 90% of the time they'd cancel at the last minute. Mothers would complain about stupid things like "one of your teachers taught my son to use his thumb and i was told he wasn't supposed to do that on guitar"

It was good money but most of it came from renting out flutes and saxophones in the fall for school registration. I totally dreaded the fall season when all the mothers would come in to register their little rugrats.

Quite frankly I pretty much hated the whole thing and was glad to quit.

Now I just teach advanced classes in private to those who really want them.