The valuable target is "iphone users" not "app store users". They're only the same because apple forbids competition with itself.
As an actual "iPhone user", I personally am going to be extremely reluctant to install things from outside the app store, let alone pay for anything. I don't think Apple's rules or the 30% cut are fair, but they did something nobody else in that space seems to be able to: they built trust.
> They're only the same because apple forbids competition with itself.
The competition is either dead, or is Google. If you'd like to blame anyone, you should blame Apple and Google for working together to establish an oligopoly.
I don't think a hypothetical Amazon, Google, Meta, or Epic store for iOS won't take a significant cut of their own - after all, again, maintaining a platform is work, and they won't do it pro bono (or they will, somehow again at the user's expense, see how Meta loooves to abuse their users as if they were the products).
I'm just speculating based on what seems to be Apple's apparent priorities, they tend to put Apple first, users second, third parties third; while other companies seem to have the latter two swapped around.
You say you wouldn't drop your prices because you know what people are willing to pay as a counter argument to saying that lowering prices would incentivize people to shop at other stores while also stating that selling at other stores would increase your margin. Well, sounds like if you want to get that bigger margin, you should lower your prices to attract people to the lower tax store.