I personally went from original in 2008, to iphone 4 in 2010, to iphone 6 in 2015, to iphone 8 in 2017. I would have kept using the old phone in every case, bu

I personally went from original in 2008, to iphone 4 in 2010, to iphone 6 in 2015, to iphone 8 in 2017. I would have kept using the old phone in every case, but: they each became too slow with os updates. In the case of the 6 I think it was exacerbated by battery issued. So probably you've taken better care of your battery? (Or stayed off ios 11) But, if you look at that record, it is: 1. Not an upgrade every to every model 2. Still a fair number of sales for apple I skipped the 3g, 4s, 5, 5s, 6s, 7