Interesting piece. But speaking as someone who was formerly a very junior VC through the dot-com era, there most certainly can be a negative spiral. The public and private markets aren't as distinct as they might appear to be. A VC buying shares in a private company at valuation X must believe that a sale is possible at a big multiple of X, and soon. Some VC will be the last investor before the company goes public or…
At the extreme, some companies in the dot-com era engaged in dubious "round-trip revenues" behavior, e.g., agreeing to buy a certain dollar amount of another company's products/services only if the other company agreed to do the same, with neither company actually needing to do so for ordinary business purposes. I don't know if this is happening today too, nor to what extent.