I read somewhere, (possibly here) that through out history, right before the turn of the century people become nostalgic. Hence the retro movement.
When it started here I have no idea as I didn't join til 2015.
As for me, I didn't do "this thing if ours" because I wanted vintage, but more like I wanted to get the bike I always wanted but couldn't afford bitd. So the internet made me realize there were some still out there to be had. And now I got 4.....but I need ONE more.