As a hobby, messing with computer hardware is probably satisfying from a few different perspectives as you have noted. Taking something that might have landed in a dump and making it useful has some appeal as does tinkering to learn more about the technology that runs our software.

However, I have to question the usefulness of this activity in general. Wouldn't your time be better spent on producing something new and productive? From past personal experience I can tell you some of that tinkering is a black hole of time, time you could have spent blazing a new trail. Let the rest of the world do the "undifferentiated heavy lifting" as AWS would say...