Not sure what happened to my first reply but anyway...
Like the above said a lot of people that grew up playing pinball now are maturing and have the financial resources to purchase their pins.
There is a similar trend in classic Nintendo collecting where games can and do reach tens of thousands of dollars. That hobby has exploded as well I don't think it's a coincidence the high value games are from almost the same era . That is where my roots are and what ultimately led me to buying pins...