Look, it's a misallocation of resources for you to own any RAM at all, and you should thank Sam Altman for letting you have some at any price.
Unfortunately there is no appetite for governments to step in.
The 3B was my Octoprint server for the longest time while I was testing the 4B for a product, but for reasons I don't really understand, the 3B isn't quite punchy enough for Klipper, when it fully should be; it drops connections to the printer. I think any of them may continue to have some uses but perhaps not till I move to a new place.
Haven't gone for a 5B or Zero 2W yet, don't really need to. Rather more interested in what happens with the Picos these days.
I think I have one live one running in my house, but I haven’t checked on it in a while and it might actually be dead now.