Depends from person to person to be honest, I would not consider it a hobby as it takes a lot of efforts at first to setup and then to maintain the Bitcoin Mining Farm. No way it's a hobby for me atleast. And if someone thinks it's an hobby, they might be having fun doing it. My hobbies are to play games, listen to music, travel etc. That pleasures me, not looking at ASIC miners running hard on heat mining sats haha.