the holy trinity of an app: 1) make users have fun 2) make users money 3) solve a real pain point if an app only does (1) and (2), it will work well short term but stop as soon as users dont make money anymore but once you have (3), users come back because they need it and you have built a killer app thats when (1) becomes optional, (2) becomes a bonus and (3) is the reason it survives