I'm not sure I buy that a typical iPhone app costs $35,000 to develop. Considering the simplicity of most apps, combined with the fact that many apps are effectively the same program with some content alteration, it seems like a really inflated figure.
It doesn't really make much difference, for the purposes of his analysis. Let's say a typical app costs $1500 to develop. If his other numbers are right, that typical app would take about 2.5 years to break even. His argument is that, on average, developing an iPhone app is, in itself, a fairly dismal economic proposition.
I agree, the chance of one app being the runaway success that affords one an early retirement is pretty remote, but the tech press loves to promote the huge success stories, and many others love to follow them.