Because I had a bad experience with android phones after they became a few years old. Either they did not get updates or they started lagging. Maybe even both. Also I loved the built quality of the iPhone 7 (silver) very much, my first one. So I’m sticking with iPhone. I had 7, 12 mini, 14 pro max. (Pro max because I wanted a bigger battery and I started to work so I could afford to spend a little more money).
If you paid a very good price,and don’t mind not having face ID than I would keep it.