I have known hoarders, including a husband and wife who currently have 200+ cats, and I have a strong tendency towards being a hoarder myself. It is a constant battle for me to throw things out or just say no to that homeless kitten, but with Zoloft, talk therapy, and the book Throw Out Fifty Things: Clear the Clutter, Find Your Life, I am keeping things under control.
My parents were hoarders, too, but because of my father’s income they could simply get larger houses so the stuff ended up in closets. In their last house (6000+ square feet) my mother’s clothing closet was the size of most people’s bedrooms. When they finally had to down-size to move into assisted living they filled two industrial-sized dumpsters, gave away stuff, and split the rest between the three kids. They still have a storage unit full of stuff, too, but we are gradually carting it away.