Apple's real problem is that people have stopped caring about keeping up with the latest iPhone. No matter which model you have, you have a solid camera, reliable connectivity, good music features, and an extensive app ecosystem. In short, your current phone is good enough.
There’s no compelling reason to upgrade. Recent "innovations" like emoji avatars and Apple Intelligence feel superficial - Siri is still as underwhelming as it was a decade ago.
Meanwhile, HomeKit is stagnant, iWork remains irrelevant, and new iPhones offer little meaningful improvement over older ones. Most users are hanging onto their devices until they physically break - and that’s a serious problem for Apple’s bottom line.