In their chapter on decision fatigue, Baumeister and Teirney revisit the idea that people have trouble making decisions because to do so eliminates options. "This reluctance to give up options becomes more pronounced when willpower is low. It takes willpower to make decisions,and so the depleted state makes people look for ways to postpone or evade decisions" (Willpower, p. 99)
Several of the hoarders profiled in Stuff hoard because they see creative possibilites in the things they hoard. When they look at an egg carton, they see a craft project. When they look at a six-foot stack of magazines, they see decoupage materials. Some of them, such Daniel in Stuff, take it to extremes and appear to view everything as of potential creative use. Frost and Steketee give a horrifying description of Daniel's sister's coop, which is overrun by roaches from the garbage that Daniel is hoarding in it; he has already filled his own, and is now taking over her apartment.
For the creative hoarders, throwing something out means a loss of a creative opportunity. They think of themselves as potential artists or inventors or handymen. To thow out the stuff that they have collected means that they have admitted that they are not artists or inventors or handymen. They cannot bring themselves to face this impact on their self-image, this loss of an option of self, so they hoard.