51 million iPhones.
And that doesn't even include the low-end of the retail pyramid. Apple doesn't cater to a big chunk of the market, and they still end up selling 51 million, with barely more than a few models.
Not only does Apple own the money-making end of the market at large, they also sell a boatload of those few, clearly-differentiated (vis-a-vis the competition) models to that market.
Given all that, Apple seems to be the only one playing the game...