This is the time were investors need to be careful. Companies go public for a few reasons. 1) to use the shares to buy other companies 2) companies that are so profitable that they don't need the money but they want to cash out some of the shares 3) they can't get any more money from private markets.

Given that a few days ago SpaceX was trying to get more money at a 1 trillion valuation and could not get it then I would say the 3rd reason.

So if the smart money is having doubts at these valuations and they have to go public the I feel we are beginning to see the start of a peek. I give it one year. When we start seeing a large increase in IPO's then every one should start running for the exits.