Like others have said, it's hard to separate the 'App Businesses' from the 'App Hobbies'. For example, I have published 4 Android apps with about 250k combined

Like others have said, it's hard to separate the 'App Businesses' from the 'App Hobbies'. For example, I have published 4 Android apps with about 250k combined downloads. On two of them I did not monetize at all, I just did them for the exercise and because I like to code. The other two I did monetize, but only in ways that kept non-time costs to $0 so it was all profit (aka no marketing, no employees, no paid services). I've made some decent money off one of the apps, but definitely not enough to live on for any amount of time. Still i consider my efforts a success, because I did it as a supplemental activity to my full-time work. If I was trying to make a living, I'd probably invest in marketing, hire a designer and/or co-developer, and monetize more heavily.