The costs outlined in the original post are probably not that far off, invest in a Sling 2 around $140K, either invest or lease hanger and office/training room, insurance, maintenance and repairs, fuel, if you are paying staff/ instructors there is workcover and other costs, admin, training and regulation costs. Now that we have added all the costs up, if it is your business you actually have to make money.
The only wealthy flight schools I have seen seem to teach international pilots, I am yet to see a general small flight training school that have spare cash laying around