It extends your radius
This is the strongest argument and the least obvious one. Someone who has watched twelve of your videos will drive 90 minutes to train with you. Someone who found you in the map pack will drive 25.
Read that way, the wasted reach is not waste. It is what you are buying. A school in a thin market has two choices. Accept the ceiling its drive time sets, or spend on being worth a longer drive. YouTube is the most reliable way to do the second.