I wonder why Google allow SCAMmers' ads. I reported them long ago but these scam apps are still there and able to advertise. Geeez!
Since I became interested in cryptocurrency I searched for "FREE BITCOIN" on Google Play and this is the first app I tested. I claimed more than 500K Satoshis last year and until now I didn't receive it. If you read the 'reviews' you could find same comments.
So, I didn't bother to install the other similar apps.
I then searched and tested apps that pay via PayPal and found a lot of scams too!
Google, oh Google, WHY are you like that?! LOL