I bought an iphone 8 when my previous phone bricked. About 2 months later, my husband bought a iphone 10, so while mine was new, it was already 2 gens old. Thus, it was cheap. I'm happy with it and will likely keep it until it dies, until the lack up updates makes it tough to use how I want to or safely, or until DH feels the need to get a new one and I upgrade to his old one. (Thankfully, he's not a person who wants the latest and greatest either, but he's slightly more interested in that than I am.
Prior to my iP8, my last 2 phones were bought used.