Nope.
> the degree will mostly be worthless by the time I graduate
A Master's degree's value is not in the information-content you managed to download into your brain. Its value doesn't have to expire as a domain advances. As with anything academic, most of the value depends on how much sweat and time you put into the thing (independently of how good the classes or profs are), and if you do it right, your competitive advantage will be in having learned how to learn better or faster.
> The degree would mostly be for personal knowledge/fulfillment
Assuming you can afford to study, and to do it well, this is the only thing you need to focus on.
> Another alternative I’m considering is learning HVAC repair as a fallback career
This comment makes me wonder whether you're being honest with yourself about what your motivation is. Nothing stops you from learning about HVAC as well, if you're interested in that.