Is there something unique about the generation that grew up with the original trilogy? There are exceptions to everything, but for the most part I don’t see older or younger people devoting as much time and disposable income to a movie, especially in the form of plastic figures, ships, and helmets to display on a shelf.
I don’t think so. Do you follow any other fandoms or film franchises? I’m as much a Godzilla fan as I am Star Wars and there’s a very strong collector base in that group and they spend every bit as much (maybe more) as the typical Star Wars collector. And I know there’s also big collecting fanbases for Doctor Who, Star Trek, James Bond, Harry Potter, comics (marvel and DC) and on and on. And many of those groups span multiple generations going back to at least the baby boomers. And prior to pop culture there were collectors of many other things (art, antiquities, fossils, naturalists, etc.)
If anything, I think what’s unique these days is the large amount as well as the incredibly high quality of the items available. And that’s all driven by the demand, which seems to grow more and more every year.