In the Mr. Pinball Price Guide, there's an interesting figure: 1 in 100 homes in in the US have a pinball machine in them. I read the entire guide, back to front, because I'm obsessed and saw this factoid in there. I thought that was a pretty surprising amount actually. Growing up, I never knew anyone with a pinball machine in their house, but by those numbers, that would mean almost one house out of any large neighborhood would have at least one in it.
Goes to show there are a lot more people with pinball machines that aren't necessarily "pinheads" out there. More often than not, this type of owner is the absolute best person to find with a machine for sale because it's usually lightly used and they don't realize the recent pinflation.