Quoted from Charlemagne1987:people who are buying them as investments will eventually realize that pinball machines are toys and they are meant to be played with and enjoyed!!!
The hard realization will be when they have to find someone to fix them. Lots of people jumping into the hobby have little to no electronics back round and few mechanical skills. Only been back in the hobby for 2 years and its hard enough to get the motivation to fix my own machines let alone want to go out and fix somebody else's. I used to think this would be a great retirement business until I saw all the different MPU schemes, parts ,actuators etc.... and people will pay you handsomely, but for me it simply was too much effort and not worth the time you had to put in and what your actual earnings would be.