Yes you are probably right but the thing is that if he have an interstitial ad on app start then he had more then 10mil views and maybe many thausend's clicks. So you can make lot of money from such a simple app.
It will not last forever but still profit can be made.
lets put it to a minimum of 10 million and that it exists 5 years. that's 2/y.
that equals 5479 installs per day?
that smells like these chinese people with 100+ phones doing installs & uninstalls all day.
These posts mean:
develop something that excite curiosity, although it is worth nothing.
No servers, multiplayer... without much brain fatigue!