What to do with a build up of old desktops/pc's from over the years?

short version: i have old desktops, can't get rid of, i need legit use case suggestions.

long version: So at one point i got a pc and then i had to upgrade, rinse and repeat a few more times., now i have a bunch of desktops and pcs that are old or dont work. most of them work and i will focus of those for now, they're just old and outdated. What can i even do with a bunch of old computers that may be useful or fun.

I also cant get rid of them at the moment due to life and family holding onto them for some reason.

Im up for suggestions, i would share some specs they range all over the place and i forgot most of them.