Yep! I kept my iPhone 3GS from 2009 to 2016 (almost 7 years), then I bought an iPhone SE pretty much immediately after launch which I’ve been using happily ever since (almost 6 years now) 🙂
I guess I also used a second-hand HTC Desire Z for a few months in 2013 when the 3GS’s screen broke, but the sliding mechanism died on that pretty quick and the 3GS was still smooth on iOS 6 while the newer Z stuttered on stock Android 4.2 ROMs so I fixed the screen and switched back.
I honestly have no idea why I kept the 3GS for as long as I did, except that at some point it became sort of a fun challenge to squeeze as much useful life out of it as I could. I also had a 1st gen iPad Mini for a newer and larger iOS device when I wanted, which also took some of the upgrade pressure off.
As for my current SE: unlike the 3GS at 6 years old, it’s still getting software updates and is butter-smooth on most apps and websites. I also really prefer a smaller phone I can use one-handed (my partner regularly falls asleep with my arm around her, meaning a single-handed phone is useful to pass the time until she rolls over), and I do most of my media consumption on my 27” iMac or a TV so I don’t feel I’m missing out on something larger. The only thing I’d really like to upgrade for is a better camera, but that’s not worth an extra ~$500-800 CAD to me just yet for an SE3 or 13 Mini. Maybe when the SE stops getting updates.