Do you have sources to back that up? That sounds unrealistic to me.
More than enough. Top grossing apps/games well about 90% of them are making a million or more a month and even more on ios. One of the devs on ios is making 5 million a month. Most of the research can be found by using google. A company known as TinyCo makes about 80,000 dollars a day. If you are into app devolpment to make money then you need to do research first to see what is making it and whats not.
Here is an example, my story of course. About 6 months ago I started working on a regular app thinking it was going to do really well. I did my research at least once a week to see if there was any new competition in my app category, sometimes there was so I would keep adding more and more stuff to make it the best on the market. Well guess what as of 3 weeks ago I stopped making my app because of the staggering numbers I found out that apps like mine were only bringing in around 5 dollars a day on free with ads and around 500$ in sales at most in 1 month.
My app was based towards pokemon. Yes I know some people say that is stupid but when I first started to do my research on pokemon on the app stores both ios and android, there was one that had made a total of 50,000 dollars in a month and a half, but for some reason the guy took it down.
Anytime you start to make an app you need to always do your research first. If you need any help I could make a full guide on how to go about this but only for the people who are in it to make a living. But so far from my research I have seen that it is 97% games that are making it really big, there are a few non game apps that have made it big, for example beautiful widgets on android has grossed around 6 - 7 million dollars.