Throughout history there have been many instances where some the valuation of a product goes through the roof for no good reason - the Dutch tulip bulb (1600 's) is one of the most famous examples. A book just published (The Great Beanie Baby Bubble) described a more recent (1990's) example. The book is reviewed in the current (Mar 22, 2015) issue of the NY Times Book Review. What struck me was another book review in the same issue (The Age of Cryptocurrency) describing bitcoins. My reaction was - is this another bubble? To me bitcoins have no intrinsic value - so what happens when other people start thinking the same way?