Most money making apps are based on fake promises, they are simply bluffing, they have a aim to find loads of people to their platform and probably pay very few new members but after a while they will stop paying, few paying apps that I knew of requires passing some surveys and they are available for people in america only
https://us7.campaign-archive.com/?u=9c41c4c645b390310192f0ab5&id=93e004ea58&eThe apps make the user experience pretty good at the beginning to get the users on board and then afterwards they try to monetize. Idk if that's in your thinking OP.