There is a massive market for high-end, high-cost phones. The pricing structure Apple is using will not impact their sales volume at all, but certainly will increase their profits and they know it. US, China, or any other market have more than enough consumers that won't blink at the price. And for those that do balk at price, there will be plenty that put it them on credit.
Apples only concern needs to be the perceived and real value of the product they sell. If the masses like and want it, they will buy it. Me, I want a new iPhone badly, have the funds, but won't buy it due to poor styling choices made by Apple - specifically that nasty notch.