Note that the mantra doesn’t say the market can stay irrational, it’s just a warning that if you are predicting when irrational failure will produce the expected results, you can be in for a bad time. So if someone is thinking about shorting a bunch of the heaviest bubble stocks and expecting to win, well, they can get screwed as the bubble sustains long enough to screw them and then pop.
Note that the mantra doesn’t say the market can stay irrational, it’s just a warning that if you are predicting when irrational failure will produce the expected results, you can be in for a bad time. So if someone is thinking about shorting a bunch of the heaviest bubble stocks and expecting to win, well, they can get screwed as the bubble sustains long enough to screw them and then pop.