There's no mystery here. The huge glut of sales only lasts as long as it takes for everyone that wants one, and can afford one, to discover they want one and then buy one.
No market grows perpetually. Any capitalist that behaves with such a belief (that increases can be perpetual) is a fool. Of course, that's most of Wall Street.
Don't worry, we poor pee pull are still working up to it. I'm slated to buy mine this week finally (after iOS 7 put me off last year).