To me it is a space issue. I can only fit 7 games into my gameroom. Currently I decided to buy pinball machines based on my favorite pinball designers. My rule is one designer per game in my little collection. In this way, no game will feel the same in my collection. I normally buy or sell a pinball machine in every 8 to 12 months. I am happy with my collection but it is far from perfect.
My games
BSD, TSPP, NBAFB, TZ, CFTBL, AFM and Ironman.