Another things is humans have a problem with dealing with "sunken costs" (http://en.wikipedia.org/wiki/Sunk_costs
Some economists say that Sunk costs are not taken into account when making rational decisions.
In the case of a movie ticket that has already been purchased, the ticket-buyer can choose between the following two end results if he realizes that he doesn't like the movie:
-Having paid the price of the ticket and having suffered watching a movie that he does not want to see, or;
-Having paid the price of the ticket and having used the time to do something more fun.
In either case, the ticket-buyer has paid the price of the ticket so that part of the decision no longer affects the future. If the ticket-buyer regrets buying the ticket, the current decision should be based on whether he wants to see the movie at all, regardless of the price, just as if he were to go to a free movie. The economist will suggest that, since the second option involves suffering in only one way (spent money), while the first involves suffering in two (spent money plus wasted time), option two is obviously preferable.
Many people have strong misgivings about "wasting" resources (loss aversion). In the above example involving a non-refundable movie ticket, many people, for example, would feel obliged to go to the movie despite not really wanting to, because doing otherwise would be wasting the ticket price; they feel they've passed the point of no return. This is sometimes referred to as the sunk cost fallacy. Economists would label this behavior "irrational": it is inefficient because it misallocates resources by depending on information that is irrelevant to the decision being made. Colloquially, this is known as "throwing good money after bad".
This line of thinking, in turn, may reflect a non-standard measure of utility, which is ultimately subjective and unique to the consumer. A ticket-buyer who purchases a ticket to a bad movie in advance makes a semi-public commitment to watching it. To leave early is to make this lapse of judgment manifest to strangers, an appearance he might otherwise choose to avoid. Alternatively, he may take pride in having recognized the opportunity cost of the alternative use of time.
So if you have STUFF, even stuff you don't use or don't like, you don't want to just throw it out because you COULD GET MONEY FOR IT or SOMEONE COULD USE IT or I MIGHT NEED IT.