Changing screens is quite a common operation, there are like half a dozen repair shops within a five mile radius of me that will do that quite happily. Batteries, less so (probably because they're harder to damage).
The industry's profitability? Not my problem. I'm happy to pay a fair price for a decent phone, but having bought it I will keep using it for as long as I can extract any sort of value from it. Anything else would be borderline-criminally wasteful. Even my nine-year-old Android, the one with the forty-minute battery life, is still in use as a backup device.
Annoyingly, the old iPhone still has an amazing battery life. It's a full week now since it went dark, it hasn't been charged at all in that time, and yet its blasted alarms still keep going off...