I think it depends on the scale. If your largest monthly expense is your electric bill; its not really a hobby any more.
yeah this is pretty much the case.
In the dead of winter I have done 690 usd for a power bill running 22 gpu's and 11 pc's
Kind of not a hobby at that point.
Now have I made a lot of money since 2012 no. Maybe 7k in 3 years and 3 months .
So it is a business but not too big in my case.
If you ask me, any hobby that has a potential for profit is fantastic. People spend tons of money on other hobbies that have no profit potential at all. As long as you're enjoying what you're doing and having fun. Sure mining might not be the most exciting hobby. Really once they are set up and running there's no fun in watching the lights blink and the fans just spin and your bitcoin wallet balance increase at a glacial pace. But some people just like playing with the new hardware and tweaking things to get the most out of it. To others hash power is like horse power. You can never have too much of it. In the end this has taken up a lot of my time and I probably made some money in the long run, but if I didn't do this I'd just end up spending money on another hobby that keeps me busy but with no return. So even if I lost say $1000 on mining, I would call it the cost of my hobby.