Well, it's the monetary stimulus going off scale. The amount of money being printed by the Fed is ridiculous, and it causes all these bubbles - and a lot of people think that they sit on a lot of money and plan their retirements on spending it. Not going to happen because this money - like home and stock values - doesn't exist, it exists on paper only as long as not enough people are trying to spend it.

System would be balanced if seeking profits and seeking exits was similarly valued and respected, if VCs would invest money looking for stream of dividends as much as exit/IPO of the company... But that would take average P/E about 5..8, not 25-30 it is. Till then, and as long as "revenue business" is a derogatory term, we can know that startups are little but a generational Ponzi scheme.