learning that most people didn't have a "back up computer" was when i began to re-think my career decisions in IT

Ive never had that happen on linux.

On windows though, it was once a year. And it wasn't even anything I did half the time. When are we going to stop pretending windows doesn't ask more if you to have it working properly?

This doesn’t happen on Nixos thanks to rollbacks ! (I guess unless your computer has never been in a working state at all, or if you erase the disk)

To a slightly lesser extent, that's also true of Windows - severe malfunctions are less likely to happen, but when they do happen, fixing them is almost always an absolute clusterfuck, and when it isn't, it's downright impossible.

Just use Tumbleweed or Fedora...or any other distro with amazing brtfs support.

That alone has saved me from myself more times than I want to mention.

Lmao. I thought I was the only one. I have like 5 USB sticks with 5 different distros on them all tested and working. I also have a laptop with bazziteOS so the chance of it breaking to no return is very slim. That way, I can fix my desktop if it breaks.

One does not simply Linux without having a stable backup computer. 👌

This was true for Windows as well.

Question: do the backup computer(s) have to be in a functional state themselves?

I always have at least one partially built computer xD

Nah now you just switch to a TTY with a bunch of sick Rust terminal tools, or if its really borked you boot into recovery mode and mount the old filesystem and do magic spells at the filesystem until it works.