It's not the customer's job to pay you forever bc Apple wants a developer license. It's the business's job to make sure it's sustainable with the costs that it has / has chosen to bear.
That's the backpressure on business models - they're not all viable. Just because you _could_ add in a bunch of servers and cloud costs and whatever, doesn't mean it's inherently justified.
The problem is more that it's gotten _so_ cheap to run, that charging each user a seemingly-nominal 5c/day fee doesn't feel bad to an average person for a chance at value. And at scale you get enough people who figure "ah it's not that much", and end up with massive profit margins. Profiting off the disparity between the individual choice and the aggregate.