Hey Daniel, I think what you're trying to say is that your friend purchases established apps in the Android Market, does marketing and user acquisition for them, and tried to recoup his investment. Is that correct?
If this is the case, I can tell you right away that it's not going to be a sure money maker without some serious knowledge of the Android Market (how to market on it, etc), some concept of what makes a good app (app design), some idea of what trends are taking place, and a bit of startup capital. I don't think this is necessarily a good career, but I'm sure that individuals with at least two of those four things can take a crack at it. I'm guessing that his knowledge of Android development helps him make minor tweaks and changes to the apps, which in turn makes them more profitable as well, so it's a long list of skills that he is leveraging to make this happen