I agree for the most part: yes I think bitcoins are overvalued, they will go back down in price, most of the recent increase is speculation, etc.  However, I think you fail to take into account the rabbid 'fanboy' nature of many people involved in bitcoin.  They are so zealous about seeing bitcoin succeed, they often do irrational things to try to 'keep bitcoin alive', eg. mining at a loss, holding bitcoins to artificially reduce supply, buying bitcoins to keep the price afloat, accepting bitcoins for items at less than market value, etc.  So while I think the price will come down perhaps significantly, I think there is a core of fanatics that will keep bitcoin afloat to some degree despite any rational reason for doing so as compared to stocks, etc. where people are merely in it to make money.