Self-Storage Abhorrence

I've noticed a new phenomenon. Growing up, I never saw a single one of these places, and now Self-Storage and other such businesses have been cropping up all over the place. There is one in Cambridge, and I saw at least four on the way up to Bancroft last week. I can only think of one practical use for these places: If you are moving and you need a place to store your stuff whilst you find a new place (or in the case of students, if your parents live far from your university/college and you don't want to pay rent in the summer), this is a very smart solution. However, it is simply impossible that enough people are in this situation to justify the number of Self-Storage places around. So what's the deal?

My immediate thought is that people have so much junk that they don't own a place big enough to house it all. It's like putting an extension on your garage when your garage gets filled up with all your crap. But at least there would be the illusion that the stuff in your garage is somewhat useful - it's at least close at hand. If you are putting things in an off-site storage facility, it means not only that you have stuff, but you have stuff that you hardly ever use! Because, even without hard evidence, I can pretty much guarantee that the space left by the stuff being moved from the garage into these storage places is being used by something else. If you had the room, why would you choose to pay someone to house it for you?

If I think hard, I can think of seasonal sporting equipment and...nothing else that it would make sense to put in those things.

If anyone has a rational explanation for the explosion of Self-Storage, I would love to hear it.