Look at the prices of what Jay’s is selling. He caters to a very rarefied clientele and one that is likely of an age advanced enough to be able to afford that stuff and advanced enough to be approaching death at the same time.
As for demographic collapse, no other country can compare to China. Of course, China is also facing financial collapse. Used equipment sites in China will be vast in number. This could ultimately be one of those situations in which high end equipment can be had for low prices thus jump starting another round of audiophile discovery and enthusiasm.