When you return the device, it needs to be in mint condition. You now have a credit obligation with Klarna, whereas on the pervious system, there was also 0% financing but it was bundled AppleCare+.

I don't think anyone will ever excercise the buyout option since the phone will never be worth more than the buyout price. And like you're saying, this program does not make sense unless you are upgrading every single year.

I mean in any case, every option looks defensible once you've accepted the premise that you need a new phone every 12 months. Any minute differences in costs are just rounding errors. Like I really don't think someone upgrading every year is going to have a significantly different retirement income because they saved $1200 every year by not buying the iphone outright. It's really just a convenience thing, not a financial decision.