I think people have been too greedy with bitcoin for months. The price has risen from $12 to $120 since the beginning of the year even before the last leg of the run-up. If bitcoin "only" doubled in price every year it would be a great investment and would actually give the bitcoin economy time to grow.
I don't think it is true for miners. Most of them (who don't have free electricity and operate GPU rigs) need at least $50/BTC price to don't run in the loss.