[unsined]

I learned a lot of *NIX stuff just by way of introduction through setting up a fileserver to host Plex, network shares, music server, etc. Doesn't really fall into any of your categories. It's more like:

4. People who upgraded their PC and have an old PC that is currently doing nothing (but could).

Sure I could have bought a NAS, but that would have cost more money and I wouldn't have learned nearly as much. And I wouldn't have been able to transcode streams.