Update:
Earnings: $60-90 daily - its passive income. I didn't spend any time on the existing apps, so I think its pretty good.
Work progress: I published 2-3 iOS apps in the past few weeks which brings me around $10-20 additionally.
Ad spent: $0 - I didn't spend any money on app installs in the past two/three months. All the earnings are from organic traffic only.
Whats next?
Currently I am reading a lot about mobile games. How to monetize them correctly, how to keep users active, etc. all that jazz. Its really complicated and there are so many things to consider. One thing is for sure: If I make mobile game, then I don't want to randomly publish shitty games, I want to make really good ones. Ones that I can easily scale with a great ARPU (average revenue per user). These are all things to consider. Once you make a game where you earn more money than you spend for app installs, its super easy to scale. Basically, its just a numbers game.
About the total earnings since I started this thread:
Its been around 14 months since I started this thread and the apps alone gave me a profit of around $25k so far. This is after all I spent for app installs, keyword installs, etc. The profit could have been way higher (at least double amount!) if wouldn't have spend a significant amount of time dealing with Google (app removal, account termination, etc.). Its somehow funny that apps that NEVER caused a single problem on the Apple App Store are always deleted on Google and they keep removing accounts for ridiculous reasons.
So what I am planning to do with the profit? Well, I could use it to develop other apps. Especially when it comes to setting up the backend I am a real noob. Or I could also use the money to go into other niches, for example ecommerce. Maybe I will do both.