The possible problem is perhaps mainly due to the 'teachers' having to find new clients, and other rising costs which are effecting everyone.
In similar vain. A friends daughter runs a fairly successful dance school for 5 year old upwards, but after 12 years in business she considering closing down altogether, or just running reduced classes from much smaller premises.
Even the local amateur boxing club, which as been running for twenty plus years from original start-up premises, have had to find new premises twice in the last 12 months. In this case its not the loss of membership, because the membership as increased and there is a waiting list now. Its just that the bills are becoming more difficult to pay, and landlords/ publicans have other ideas.
Maybe because the cello teacher is fully booked and turning customers away.
It's a fundamental principle of the free market - if you have a product that's in high demand and you can't supply enough of it, increase the price until you achieve a balance between demand and supply.