Put it in the drawer/closet to repurpose for another project, but never get around to it.
Sometimes due to lack of time, or sometimes just because I have better options available.
I had so many things that could've been done with an old laptop/desktop that just got loaded onto a VM or SBC instead.
That way is cheaper on electricity too.
Home Assistant, OPNSense, OpenWRT, Unifi Network, Omada Controller all run on my Proxmox VE server. Frigate and Nextcloud will ultimately end up getting added to that same machine.
I have a Libre Computer SBC with a POE adapter in each building to run my Z-Wave network.
I was considering setting up an old laptop as an Octoprint server when the Raspberry Pi shortage was ongoing, but it was less effort to just get a long USB cable to my desktop and run it there.
So my old laptop is still in the closet gathering dust.
I have a bunch of old MP3 Players, Headsets, VGA cables, Cell Phones, Mice and keyboards, etc that I really should throw away but haven't had the time to organize that I can at least keep the 1 or 2 best ones as spares. I have more old monitors lying around than I know what to do with.
I have enough old hardware lying around to build another 3 desktop PCs, but VMs are easier and SBCs sometimes more convenient.
It is at least nice to have a spare GPU or power supply lying around to get a new system up before all the parts have arrived or to swap out for troubleshooting.
I have plans to turn one into an HTPC, one into another server, and one into a workstation in the outbuilding, but I haven't maxed out my existing server yet and I use my laptop in the outbuilding, so I don't really have a need right now and the hardware will probably be obsolete by the time I do.