I think the 'collecting' part just happened.......I mean, I started out loving music way back in the 70's...but I was too young to buy my 'own' stuff. But, when I hit like 8th or 9th grade, I did the Columbia House thing like some of the others I've read. That got me 'started'...I guess. And it was different genre's.....I LOVED the New Wave stuff coming out at the time...Gary Numan with his synth stuff....Depeche Mode.....Duran....and at the same time, I was already a HUGE KISS fan....but albums by Quiet Riot and AC/DC took me further down the metal path.
I had an 'average' amount of music in the early days....but after high school...and into college is when I started to 'collect' a bit more. And when I started reading Metal Edge...well....the Rock On the Rise section always had me writing to bands to get their demos and releases, etc. THAT is when I started to really pick up steam 'collecting'. Metal Edge lead to Heaven's Metal, Screamer and other mags and fanzines and I was getting stuff from all over. Meanwhile....I was starting to buy almost every release that would come out that was melodic hard rock/glam/sleaze...etc.....and my collection expanded....and as my collection expanded...so did my appetite for more.
The internet provided that impetus...as now I could actually contact people from all over....faster....and start trading, buying, etc. on a much larger level. eBay comes along...and adds icing to the cake.....and my collection grew exponentially....
The fact that I have that 'collecting' gene doesn't hurt......as I 'collected' comic books....beer cans...and football cards as a kid....and then as an adult, it is mostly die cast cars....KISS memorabilia....and music!