Are iOS apps for real users, or just for us?

Forget the philosophical question. When I see sales figures, hear that 100% of our developers have iPhones (e.g. I had to test on BB or Android for them) and then go out on the streets and see even Blackberries, I wonder. So, some back-of-the-envelope math. The Bureau of Labor Statics has neat info. I am sure it can be sliced differently and I may be doing it wrong, but combining some programming and analyst categories, I am comfortable saying there are close to 4 million developers in the US. I am having more issues getting solid numbers on designers, but I am comfortable saying maybe half a million, if you include general graphic designers. I mean, who does only print these days? Assume 80% carry an iPhone. I think this may be conservative, actually. 4.5 million people, times 80% is 3.6 million devices. Handsets only. Devices are even harder. But grabbing some figures, iOS is around 30% of the smartphone market in the US. There are 91 million total smartphones in the US, so 27 million are iPhones. That means around 1 in 7 owned by designers or developers (not even getting to the others in your office. So, are you designing for the rest of the people in the world, or for your co-workers? I should ponder more sometime what this means.