They aren't very interested in taking VC-funded companies money because it will be like taking something out of your right pocket and putting it into the left one - it doesn't do anything to prevent the bubble from popping.
External money (from outside the bubble) however is very important since it's the only thing that will stave off the eventual cascading failure of the industry as all these unsustainable companies (who mostly just pass their VC money back & forth) start falling like dominoes.