To justify fairly high PE ratios, you need big growth potential. Once a company like google or Amazon has pretty much saturated the potential customer base, inv

To justify fairly high PE ratios, you need big growth potential. Once a company like google or Amazon has pretty much saturated the potential customer base, investors are going to want to see more efficient conversion of that customer base into revenue, or else the share price is harder to justify. Of course this is a simplification, and monetary policy has more to do with the the current contraction.