I believe PG's point is that creating a company as successful as Groupon or Zynga from scratch requires an incredible level of psychological and man-hour commit

I believe PG's point is that creating a company as successful as Groupon or Zynga from scratch requires an incredible level of psychological and man-hour commitment, in addition to constant creative and iterative idea generation. The idea that they are pump-and-dump schemes is absurd in light of this essential truth.