Just like title says, for a phone you probably won’t keep beyond 12 month, is it worth it to spend money on a decent case? Not interested in any of those cheapo amazon cases.
I typically buy an Apple case (silicone one this year for my iphone11). I may buy one or two amazon cases if I want to change things up during the year.
If you don't mind throwing the phone away after 12 months, you should protect the phone as if it were your own, because it is. If you break it, you won't get the trade-in credit you seem to expect.
Being on the iUP program is hardly a reason not to use a case. If you want to change your phone after a year you want to make sure you get the maximum value you can when you sell your phone. As for those cheapo Amazon cases as you call them some of them are as good as if not better then the more expensive cases. I’ve been using them for years and they’ve served me pretty well.