We do apps for the fun of the users.
We do apps for the fun of doing apps.
We do apps for the OS we like to develop for. Currently doing apps for iOS is the best fun for us. This might change in the future - we can do iOS, Android and Windows Phone.
But why do we sell our apps instead of giving them away for free? Developing apps costs money. Developer programs, computers, mobiles, tablets, other equipment, servers, power and internet connectivity are not for free either. We need to cover our costs. Unfortunately, selling the apps did not earn us a fortune yet.