Supply and demand dictate prices. When I started this hobby in 1975, pinball was very active and demand was pretty high. Prices seemed high then. Then, videogames came along, and interest waned in pinball. From that time up until I stopped buying machines in 2000, prices were reasonable for new machines and rock bottom for older unpopular machines, particularly Gottlieb System 80 machines, and I, like many other old timers familiar with the industry and the manufacturers, picked up used machines for basically nothing. I think the most I ever paid for a solid state DMD machine was $2200 for a Medieval Madness.
I've watched interest, enthusiasm, demand, and prices rise over the last 15 years, and comparing what I paid to what the same games are selling for now is just ludicrous.
But if people want to pay that much, that's fine with me.