I don't disagree that growth companies require and should be afforded higher PE's. You are correct.
You reference the internet boom of the late 1990's. Even the 2 most successful companies from that era (AMZN AND GOOG even though GOOGLE WENT PUBLIC LATER) eventually collapsed as a result of the bubble. They ultimately recovered because they were real companies. However, even those 2 companies experienced a price collapse. I was a major player and I remember people saying that Barnes and Noble would crush AMZN and anyone can do search. The naysayers were wrong. However and even with their crazy success, both companies had price corrections along the way. If you can, find an accurate AMZN chart from 1999-2002, take a look at the price correction. It will shock you. The same will happen here. In the meantime, the correction may begin at $1400 a share