When pinball started to fade away (late 1990's) you had many operators getting out of the business and selling their routed pins. So now you have a great situation for owning your own pinball machine: lots of pins available to buy at a decent price, and the lack of pins to play in the wild.

As more and more people have started getting into the hobby, those supplies aren't being replenished by older routed machines in the same numbers. Supply has gone down, so the prices have gone up. Stern, JJP, and others know this so have raised their prices accordingly. This has made it even tougher for someone to make money on routing pinball machines, and the home collector market has gotten more expensive. Less routed machines to buy and higher priced NIB games.

I think that pinball collecting is probably at it's peak or right around it. It seems like weekly, someone is posting about getting out of the hobby.

I don't see a resurgence in pinball in the wild. It's just not profitable enough to make it worth someone's time.