That’s not true. A lot of people wait until their phone no longer works to upgrade. And also, something being a cash cow at the moment does not mean that thing

That’s not true. A lot of people wait until their phone no longer works to upgrade. And also, something being a cash cow at the moment does not mean that thing will continue to be one. Since the iPhone 6ish, iPhones have become “good enough”; there’s not much to differentiate each model from the previous as there was with, say, the iPhones 3GS and 4. The iPhone 13 just doesn’t have much going for it compared to the 12.