It’s not really an “extra” $112 is it though? You were always going to pay $670 for the iPhone X you have and you’ll still only pay that.
If you choose to upgrade 2 months early because the next iPhone are available earlier, and bring forward 2 monthly instalments, that is your choice. But Apple is not asking/forcing you too and is still not charging you any extra over what you already agreed to pay them.
Personally speaking though, anyone who paid $999+ for a smartphone needs to give their head a little wobble anyways, so not really surprising so many struggle to grasp how their repayment plans work.
Are you insulting my intelligence just because I have enough disposable income to enjoy something that I'm passionate about? Seriously? Get off your high horse.
There are plenty of people that spend money on things that I think are ridiculous, such as high-end luxury cars. You know what my car payment is every month? $0.00. I pay cash on used cars that I get good deals on. But I don't go around on car forums telling people they have a screw loose because they bought something they're passionate about. I put my money where I want to, end of story. It's none of your concern, full stop. I understand how repayment plans work. I use it for the convenience. I don't have to mess with selling on Craigslist any more. And now they just ship me my new iPhone with a return box for the old one. Easy.
I run a very tight budget and put a lot away each month for investments, retirement, and my children's college funds. I grew up with two idiotic, abusive parents who had mental issues and were always poor because they didn't know how to manage wealth. I know how a freaking repayment plan works.
Since you're a world renown mathematician, allow me to break it down in terms that even a potato would understand:
September: $112 for old iPhone X + $56 for a new iPhone X payment
October: $56 for iPhone X payment, etc for the next year
If they had instead released last September on-time, this is what would happen:
September: $56 for new iPhone X payment
October: $56 for iPhone X payment, etc for the next year
Can you honestly not see the difference here? I'm paying $672 for a ten month period instead of a twelve month period. Over the twelve month period September 2017-2018 I'm paying $784. That is how you budget. I did not budget for that increased cost. Can I cover it? Easy-peasy-lemon-squeazy. But that's not the point. It's about them potentially screwing over their best customers who pay them annually at launch for the most expensive iPhone they make.
I always get the new iPhone at launch. Since they've had the upgrade program, the launch has always been one year apart. The framed it as being easy to upgrade every year. Last year they ran late and I had to pay two months extra on my iPhone 7 before I could get my hands on the iPhone X. I could wait until November, but why should I have to just because they ran into manufacturing problems? I've been doing this since 6-29-07.