In 2024 I bought a used (2021 era) Dell for $400 to use as my home server. Just the ram that it came with now routinely goes for $600 or more. I'd sell it, but then I wouldn't have a server...
I did end up selling my best GPU, an RTX 4080. I had it for over three years and got ~80% of my money back.
You mentioned the COVID car market. The dealer we bought our Prius from sent us a letter during COVID offering to buy our car back sight-unseen for more than we originally paid. I regret not taking that deal, but at the time you couldn't replace it so what choice did I have...