Quoted from Whysnow:

I will say that it does not hurt that in 2 years time I have gotten pretty lucky with some good deals (1 in particular; MM) that helped to offset the cost of my entire collection when I sold.
I currently have real $ of 11250 in my entire 8 pin collection.
If you add up the 24 months of saved drinking out at an avg of $100 per month, that knocks it down to $8850. Take off another 1000 in games played (yeah I do not play that much) brings it down to $7850. Take down the value of a pinball education of various course I could have taken at local community colege and still not learned what I have already, est value 5k and that brings it down to $2850.
I'd say if you think about pinball as a normal hobby, it puts it all in perspective. I have gotten at least another $2850 of enjoyment out of pinball.
Things are a lot more fun when you are not concerned about the value of a game
That was part of the reason I had to sell MM. It made me think about $ value instead of fun value.