What is wrong with people? It's a dot-com bubble all over again. Groupon take 50% from the price of the 'voucher' and have still managed to post some eye watering losses (once you adjust for their creative accounting practices). From what I hear retailers who have taken part are wishing they hadn't since the customers are only in it for the deal and never come back again.
Facebook and Google are worth billions. Groupon is not.