Still using my first smartphone my mom bought me (iPhone 6S) since 2015; which would make this about 6 years and counting. Before that, I had a traditional flip phone for about a few years.
I have definitely had thoughts about upgrading to a new phone though, as of late. My phone says the battery health is working at 81% maximum capacity to when it was new, but it feels much worse than that. Battery percentage can drop over 10% in just a few minutes of light use. This was then followed by my phone case (a plastic case which has held up remarkably well over the years) peeling apart a few weeks ago…
e: All that said, I haven't been caught up in the whole smartphone upgrade race. I had the option to trade-in/upgrade my phone when my parents changed phone carrier/plans, I declined while my parents took that opportunity. And my sister I'm pretty sure has gone through at least a couple of different smartphones already due to various mishaps.