The younger generation seems less concerned about amassing/collecting.
That is a broad generalization, there are still hopeful signs, but I think the percentage has definitely dropped.
I look at stamps and trains. On the downturn, probably never come back. Are Comics next? Are the movies and pop culture references enough to keep them relevant with newer generations?
I tired to get my nephews into comics in the 1990's. They both amassed a long box or two in their time, went to shows, got Stan Lee's autograph. But they have stopped cold turkey now, both approaching 30 years old. Started selling off some of their stuff, don't actively buy comics. Not sure if they will ever come back.