It is a real sickness and it appears it could be hereditary. One of my coworkers is married to a hoarder and her daughter has the same issue. Her husband buys endless numbers of workroom tools, some that he already has many times over.....he just throws them in a shed that is piled high with tools. She has to sneak in there and throw some out every once in awhile and he doesn't even notice, he just keeps mindlessly buying more and piling them up!
I have not seen "Hoarders" but I can imagine. My wife does watch a lot of "Clean House" on Style - a lot of these families clearly have issues with their buying obcession, keeping obcession and an odd sense to be able to live with rooms and rooms full of clutter. I don't get that.
I may have a collector mentality (comics, music, DVDs, etc.) but I also have a strong sense of organization. Everything has to be in a neat and orderly place. Seeing stuff just thrown around in piles would drive me insane. I'd have to organize it (and get rid of stuff not needed).