Is very simple, if you don't plan to use your body until is dead, you better sell it not too late, before it loose all the value.
Imagine that I still have my old Nikon Z6 and I will not sell it, because I don't think I would find someone who will pay me now more than $500 for that. So for me is perfect second camera. I don't care anymore if I scratch, hit or when I travel to strange destination is perfect low value item, but I can still take very good pictures.