Come on man. UBER isn't even a stock. The so-called 'valuation' is somebody's pipe dream that hasn't been exposed to the marketplace.
ALSO there will ALWAYS be stocks that are over hyped and overvalued. Cherry picking individual issues and using them to characterize the market is a fools game.
March 10 2000 the NASDAQ hit 5132.
Now the NASDAQ is still well below the 2000 high on an inflation corrected basis. Even more so considering the burgeoning size of the tech economy over 15 years.
Maybe there is an argument that things are overwrought, especially in Vulture Capitalist Fantasy Land. But bubble? Nah.