That said, I bought a fairphone about 4 years ago, in that time, I've had a bunch of issues that'd have meant replacing the phone for other non-fairphone models (this list doesn't make me look great at taking care of things): - USB charger broke after getting mortar in it - Screen broke after dropping the phone directly onto screen - Battery replacement (due to age, not my fault this time!) - Screen broken yesterday after dropping my phone onto concrete after falling over during a run.
If I'd had a Samsung, or non-repairable phone of another kind, I'd be buying my fourth phone today, instead I ordered a spare part and will repair things easily in a couple of days when it arrives.
So, hard to beat the sustainability of second hand tech, but definitely from an economical point of view, my fairphone has easily been a good call.
Of course your mileage may vary, especially if you are better at taking care of things than me.
Edit: worth saying, the fairphone 4 was discontinued a year or so ago, but that isn't the same as saying parts aren't made for it. Spare parts are still really easy to get hold of.