Here is a chart of the Nasdaq Composite, the world's main technology index. It peaked in the dotcom bubble on March 10 , 2000. The PIE ratio later peaked above 500 . In hindsight, this is widely agreed to have been a bubble. In March 2015, the index value for the first time since then surpassed the peak. Why. might some investors at that point have argued this time it's different"?.