Expanding on Rich’s point about long-term value, if we use a 3% nominal discount rate, earnings going to zero in 2020 then recovering fully mean only a 3% decline in a stock’s NPV. Less than 3% if we assume there’s a long term upward trend in earnings, which is reasonable.

While this exercise I think is useful, the market is now heavily fueled by a tech bubble that is more extreme than 1999-2000. And there’s not much sign of it crashing, since there isn’t much leverage involved in terms of debt financing, and the large owners of these stocks are true believers and also have no need to ever sell. To the extent they need cash, they can get margin loans, but they need little cash compared to their holdings.