Although this is somewhat off topic to the subject of stamp collecting, I found this recent article very interesting on what is described as "9 Completely Worthless Collectibles":
http://finance.yahoo.com/family-hom...ibles-streetAlthough the article does not mention stamp collecting by name, it does make reference to the ever popular collectibles from firms such as The Franklin Mint. As many SCF members may recall, in addition to their plates and figurines, I believe they also touted special bicentennial and/or first day covers, or gold and/or silver foil reproductions of stamps, etc., often through TV shopping channels or magazine advertisments, with a lot of people buying their wares only to find out afterwards it was worth only a fraction of the price paid (if they were lucky) or in some cases next to nothing.
The article should be a reminder to every collector -- even stamp collectors -- that we should be collecting what we like for the joy of the hobby and without expectation that it will provide the value needed to send kids to college or fund our retirement. If, when we're ready to sell, there is some profit, wonderful! But if not, it shouldn't be viewed as a loss, as there is more to collecting than just the monetary value of an item, whether it be stamps or figurines or toys or antiques (or whatever).