Many of these apps and tools do not have unique creators - there are devs who churn out apps like crazy, multiple of apps per year. Also, many do not try to make a living off of this - go figure, how much can you possibly earn with a top-10% mobile app? How long will earnings last? Seems more like a lottery to me. The article's writer means SaaS products, and I doubt that your chances of financial success are nearly as high with mobile apps you put in stores.