I have 3 API services, 2 desktop apps & 3 iOS+Android apps that I have developed over the course of 7 years after my CS engineering degree in a third world country, pretty much like the @throwawaytree here. My earnings are at average rounded converted to 6000 USD/month less server/misc. costs. I live with my parents(no rent) in a village in this state in India https://en.wikipedia.org/wiki/Kerala . I am 29. I think I have enough savings for a lifetime and most of the revenues are on auto pilot.