Why We Love to Hoard

Tom Stafford says it's often due to what he calls the Endowment Effect:

This might sound like a nonsensical riddle, but if you’ve ever felt overly possessive about your regular parking space, your pen, or your Star Wars box sets, then you’re experiencing some elements behind the psychology of ownership. Our brains tell us that we value something merely because it is a thing we have. This riddle actually describes a phenomenon called the Endowment Effect. The parking space, the pen and the DVDs are probably the same as many others, but they’re special to you. Special because in some way they are yours.

And the fix, apparently, is easy:

Now, knowing the power of the bias, for each item I ask myself a simple question: If I didn’t have this, how much effort would I put in to obtain it? And then more often or not I throw it away, concluding that if I didn’t have it, I wouldn’t want this.

(Video: You might remember the show about compulsive hoarding. If not, it's hugely entertaining.)