Mining is not what that should be regarded as a hobby. Or I can not consider it as a hobby. The reason for this is because I do not think someone will say he is mining bitcoin for pleasure. Hobbies are activities that you do for pleasure. Even if some people just like to be a miner and not benefiting from it, it is still not a hobby for such person because no pleasure derived from not benefiting from being a miner.
The pleasure I mean is the one that makes your hobbies to be recreational activities that can even benefits your health like riding a bicycle with friends, reading story books and novels, watching movies and sport events on TV et cetera.
I enjoy mining Bitcoin. I started doing it in 2011 and it has always been a hobby to me. I’ve had custom electrical work done to enable it, custom ducting, went solar, got a battery backup. I did all these things not to increase profitability or anything like that. I did it because I was having fun supporting a project I care about. I’m still solo mining for fun now and I donate all the coins I get to a community project. No concern about profitability whatsoever.