Size of the business is not relevant unless:
1) The business has a dominant market position
Or
2) The behavior of the business is likely to result in the business achieving a dominant market position
Neither of these apply to Apple. They are a minority player in the smartphone market and their market share is shrinking.
If Apple has a monopoly on their own App Store then Epic has a monopoly on their own game. Period.
So instead, people move the goalposts to an aftermarket of the product (iOS apps) and claim that Apple has a monopoly over that market instead. But every company has a natural monopoly over their own products, and by the very same logic you could claim Epic has a monopoly over the aftermarket of their product (Fortnite skins).
Who are you going to buy from without giving Epic a cut? They're the only ones offering Fortnite items.
How is that argument any different than the one Apple is making?
The physical cards cost money to produce and the retail stores will insist upon a decent cut. And then the cards are often discounted by 10, 15 or even 20%.
> the question as to what is anticompetitive and what is simply good business changes as a business scales. A small business can generally be as anticompetitive as it wants to be, while a much larger business is much more constrained in how anticompetitively it can act
The word “monopolize” is used in a specialised way in antitrust; it doesn’t encompass every exclusive right of sale, because that would disrupt many small businesses and law is intended to prevent huge businesses from dominating the economy.