"Narrow entrepreneurism" could also be mom-and-pop stores that provide a need to a local community. A lot of apps fall into this category: the might be perfect for a small number of people, whether concentrated locally in one city or country or dispersed across the globe. As with a mom-and-pop store, such apps might generate a comfortable income for a small team working full time, but won't make you a billionaire or even a multi-millionaire. And you don't need to care about changing the world, just focus on providing a good service that makes a small number of people happy.

Unfortunately winner-takes-all seems to be the dominant Internet business model, whether that's due to nefarious monopolistic actions on the part of the big players or just the natural course given the underlying technology and economics.