It long since stopped being about innovation and disrupting markets and became mostly about shuffling piles of imaginary units around so a select few could get rich. Sadly the pawns in this whole game will be all the employees holding options that are soon to be worthless... and who were convinced to take those options in exchange for taking a proper cash salary.
The only good thing this time around is that (unlike the last big Silicon Valley implosion) most of these companies are still private. So it will be really messy for some private investors and the greater San Francisco area is going to have a mess on its hands, but the broader US economy isn't going to get impacted as much. The stock market of 2015 also isn't propped up by bloated tech stocks in the way it was in 1999-2000.