To build a successful (tech) business you need to have (other than all the other factors such as a talented team, money, luck) the right expertise in technology (duh!) and domain expertise.
As obvious as this sounds — it offers an interesting insight and opportunity.
The first piece is clear — you need to have the right technological expertise (or have access to it) to solve the problem at hand. The second part is interesting: The reason why we see so many social-location-based-sharing-economy-photo-apps is that this is what most young founders know. It’s what they experienced the last four years of their life first hand. It’s their domain expertise. Solving the problems a dairy farmer, a realtor or freight shipper has — not so much (which by the way are all massive market opportunities).
Which leads you to an amazing opportunity: Pick an industry you feel is ripe for disruption and you care about and go ahead and learn everything you can about it. Expect that this learning will take time (as you fundamentally need to understand a problem before you can truly solve it). Build up domain expertise — and then bring technology and domain expertise together to create unique solutions in an otherwise untapped market. Instead of trying to fight it out with the other 1,250 apps in your category on the iOS or Google app store.
Opportunities are created at the intersection of domain and technology.