Apple doesn't have a monopoly over its "market" any more than Nintendo has a monopoly over its. Because a marketplace is not a market.
Regardless, you need to be specific as to what "abusing" means. The FTC is pretty exacting about what unfair competition is via monopoly. What exactly is Apple doing with its (non-)monopoly that is illegal?
https://stratechery.com/2018/apple-app-store-follow-up-aws-a...
Ben already has addressed this kind of defense.
> What exactly is Apple doing with its (non-)monopoly that is illegal?
See the following article. And note that this is just the tip of the iceberg. You might heard about Spotify v. Apple and the recent Hey situation.
https://www.nytimes.com/interactive/2019/09/09/technology/ap...
Not sure if you believe that Apple is on a safe ground for antitrust issues but Apple doesn't seem to share your optimism.
https://www.cnbc.com/2019/09/09/apple-says-it-changed-app-st...
If that isn't an entire market, then I don't know what is. You can't compare the Nintendo Switch or PS4 to that. Not only is there an order of magnitude more competition, but it doesn't match in scale or scope.
Apple gets to tax you when you want to find a partner. When you want to watch a movie. When you want to do your taxes.
It's not fair. It's suffocating.
Nintendo and Sony have been actively subsidizing third party developers to attract them into their platform rather than threatening them to pull off from the market. This is possible since game publishers have much more negotiation power than App developers against the platform owner. The point is, being monopoly itself is not illegal. Abusing monopolistic market power is.