More: the size of the market also indicates a certain fragility. The chance of competitors/demand/etc may mean that eventually it won't be worth enough money to

More: the size of the market also indicates a certain fragility. The chance of competitors/demand/etc may mean that eventually it won't be worth enough money to commit further effort to. If you can bring your app to a point where it's sellable and maintenance work to a point where there almost isn't any, then you have something. Edit: Also - read everything patio11 has ever written (http://www.kalzumeus.com/ http://www.kalzumeus.com/).