Just a few days ago, somene asked me to sell their stamp-collection items on eBay for them. I used to collect stamps too. I Googled "stamp collecting popularity" and found out that the hobby was dying for the most part:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwjPi7fP9MfPAhVEbj4KHUE_AY0QFgghMAE&url=http%3A%2F%2Fwww.ecommercebytes.com%2FC%2Fabblog%2Fblog.pl%3F%2Fpl%2F2012%2F12%2F1354639290.html&usg=AFQjCNG8nYQHFZ-fzF93nJvs_O6W8x0e2g&sig2=1VTYsTHa0mlxM68Uq3ayZg&bvm=bv.134495766,d.cWw

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0ahUKEwjPi7fP9MfPAhVEbj4KHUE_AY0QFggwMAM&url=http%3A%2F%2Fwww.telegraph.co.uk%2Fnews%2Fnewstopics%2Fhowaboutthat%2F8829055%2FPhilately-gets-you-nowhere-stamp-decline-sparks-fears-for-collectors.html&usg=AFQjCNEnrVdE6tYEp9zYKD7c5KOeAkaIDA&sig2=Ck2D4LfnzRW-CA0km9zLuw&bvm=bv.134495766,d.cWw

https://www.theguardian.com/money/2013/apr/13/stamp-collectors-catalogues-philately-clubs

Robert