This argument is based on the idea that stock markets should price rationally based on value, but evidently that's not really how the markets work. Share prices have -- and need -- very little connection to any "true" value of the business whose stocks are being traded. For the basic investment strategy of trying to buy low and sell high, investors win if the stock subsequently goes up and lose if it subsequently goes down. The reason for the change, if there is any logical reason at all, is largely irrelevant.
Assuming any sort of pricing rationality risks the well-known problem that the markets can remain irrational longer than you can remain solvent. It should never have been possible in a rational market for the recent WSB pump-and-dumps to work, yet many billions changed hands as a result. Not that I have much sympathy for the losers on that one, because it should also never have been possible in a rational market for the short-selling strategy that left them vulnerable to work either. Both groups got away with something dodgy for a while and then some of them lost a lot of money when the house of cards fell.
Whether this disconnection of prices from real value is a healthy way for stock markets to operate as a key element in our financial systems is a separate question, and it's one that a different and probably much smaller group of people care about.
As a footnote, it's probably worth mentioning that some businesses, including tech stocks, don't necessarily follow the traditional models for either growth or dividend payments. So although those P/E ratios might be considered very high by traditional standards, those traditional rules of thumb aren't necessarily useful in these cases, even if we only look realistically at the potential for future profits. A high-growth tech startup might have low earnings in the early days and rely on some big investments for funding instead if it's building a huge user base without yet having a firm strategy for monetization, for example. That doesn't mean it won't have genuine potential to earn a huge amount of money from that huge user base later on if it does find the right monetization strategy.
Assuming any sort of pricing rationality risks the well-known problem that the markets can remain irrational longer than you can remain solvent. It should never have been possible in a rational market for the recent WSB pump-and-dumps to work, yet many billions changed hands as a result. Not that I have much sympathy for the losers on that one, because it should also never have been possible in a rational market for the short-selling strategy that left them vulnerable to work either. Both groups got away with something dodgy for a while and then some of them lost a lot of money when the house of cards fell.
Whether this disconnection of prices from real value is a healthy way for stock markets to operate as a key element in our financial systems is a separate question, and it's one that a different and probably much smaller group of people care about.
As a footnote, it's probably worth mentioning that some businesses, including tech stocks, don't necessarily follow the traditional models for either growth or dividend payments. So although those P/E ratios might be considered very high by traditional standards, those traditional rules of thumb aren't necessarily useful in these cases, even if we only look realistically at the potential for future profits. A high-growth tech startup might have low earnings in the early days and rely on some big investments for funding instead if it's building a huge user base without yet having a firm strategy for monetization, for example. That doesn't mean it won't have genuine potential to earn a huge amount of money from that huge user base later on if it does find the right monetization strategy.