Common sense has nothing to do with anything and the IRS does not care at all about those things.  For them it is simple... If the activity/amenity is available to the public it matches the reason for our tax exemption and is not taxable... no matter how large.

If the activity is not available to the public, however, it is taxable.  If it operates at a loss, the tax would be zero. Otherwise it would taxed at the appropriate rate.

Jeff