It's estimated that Apple has 588 million users and there are 1 billion active Apple devices. Average Apple user owns owns 1.7 devices. https://www.businessinsider.com/credit-suisse-estimates-588-...

Assuming that growing income equality is lasting megatrend in both developed and developing world, brand that targets only customers who can afford premium hardware and services can be extremely profitable and provide growth without competing with market share in other segments.

edit: billion typo