If this book intrigues you (like it does me), start nowhere else but the “How to Read This Book”:
A successful iOS game makes $4,000 annually (this goes for any app frankly). A successful Android game makes one seventh of that (one third at best).
You are not a large multi-million dollar company (at least I don’t think you are given that you’re reading this book). So you don’t have the customer acquisition/marketing budget to beat this $4,000 annual average. Period.
Brutal. What’s a dev to do, then? Make lots of niche, high quality games.