I'm new to the hobby, but really starting to get the bug. However, I spend at least $5,000 per year on family travel and sometimes closer to $10,000. I can't think of a significant trip with my family that I would cancel so that I could own a pinball machine. I really like it so far, but not something that I would divert funds from almost anything else to buy more machines. I have one now and I am a bit obsessed with making it the best it can be without going nuts and putting $5,000 rims on a 2005 Ford Focus.
My kids are now 13 and 15, so ask me again in five years when they are out of the house and I may have a different answer. Of course I might not have a house by then...