As an old fart, I'm not too worried about it either way as I won't be here! However I am actively selling my stuff, accumulated over 60+ years, and I think everything has done very, very well. Anything with silver or gold has that intrinsic melt value that will always be there as long as the metal is valuable. In the 1960's, who would have thought silver would reach $120/oz and gold over $5k? Where will it be in 30 years? Who knows?
Collectibles of any kind go up and down, but long term they mostly go up, IF you stick to actual rare stuff instead of whatever is being hyped. When I was actively buying in the 60s-early 90's I bought a lot of stuff from old people. Now I am one.
You also need to remember that old people have the money and the free time to devote to their hobby that most young folks do not. I have a nephew who is almost 40 who is interested and I encourage him when I can. However with work, family, volunteer work, and life in general he has no time and not much money to invest. As he gets older he might be more active.