I go to the store. They say I get a discount if I have their club card. So some paperwork and five minutes later, I have a 2” by 4” hunk of plastic and more $10 in my pocket than I otherwise would have. But now what do I do with it? I already have a collection of similar hunks of plastic, making my wallet too fat. My option is to keep them somewhere other than my wallet, inevitably, when I want it next, I won’t have it and will be out $10.