I really don't get this whole "itch" thing. If the device is working for you, why would you want to waste money on a new one? I'm not trying to diss anyone (to each their own, for sure), but just genuinely interested in the reasons.
Because some genuinely like having the latest device every year, and that’s why they have implemented upgrade plans from carriers and Apple for consumers to take a advantage of having these options. Just because somebody has a perfectly good working device, doesn’t mean they shouldn’t be permitted to have the latest device as long as they meet the requirements and make their payments. I would say most consumers to retain their iPhones for a number of years, but for those who are more tech oriented, they do enjoy agreed to having the latest device because its optional.