Are mobile game revenues real?

Hi to everybody. I need your ideas for a problem. Please help about it.

I want to develop a mobile game and my practices are already started. I am spending to much

time for this job.

I examined google play top grossing list. Most of the games in this list designed

professionally by corporations so there is a team behind of these games. Also there are a

few games designed by just one person and I think a person can finish this kind of game in

1-2 years. For example traffic racer. Here is video of it.

Traffic Racer Record (250k points) - YouTube

Also there are a few web sites which estimating revenu of mobile games. For example

thinkgaming.com.

I could not find daily revenu of traffic racer in thinkgamig but daily revenu of hill climb

racing is around 10000 dolar. Hill climb racin is at the 126 grade in the list and traffic

racer is at 134.

My assumption is this: There is 8 grade difference between hill climb and traffic racer. So

let say traffic racer's revenue is 5000 dolar per day. Another thing thinkgamin is just

giving you estimation, so revenues are not exact amout, but at least they are doing this job

professionaly. Let say thinkgaming is %50 wrong in their estimation. In conclusion traffic

racer making 2500 dolar daily revenu. In a mounth, it is 75000 dolars.

Here is my question and contradiction: Is this job that much profitable, if yes why

everybody do not starting to develeop that kind of middle quality games.

Thanks for your helps.