Do not understand the logic. For example, I could say that the proof that God exists is the amount of time atheists spend in explaining how God does not exist etc.
It's in the way it's being done. The argument for why we should be cautious is straightforward. It consists of simply pointing out that people seem to be spending a lot of money on assets for which the price has been rising rapidly, and they're doing it based on a soft thesis of simply assuming that a past trend will continue into the future wrapped in a thin candy shell of hype.
A compelling counter-argument to the assertion that people are overvaluing tech would be a clear explanation of why the prices being spent on tech companies now are justified by compelling reasons to believe that those companies can produce value for shareholders by either delivering a portion of profits to the owner's pockets or by increasing the fundamental value of the company. This explanation would of course need to be finished off by a case for why the amount of value that can be delivered to shareholders is in proportion to price at which those shares are trading hands.
On the other hand, folks churning out lists of reasons why "this time it's different" that are peppered with buzzwords like 'transformative', but never getting around to directly addressing the actual question at hand in any sort of articulate manner, have been something of a mascot for the past few market bubbles. Consequently, seeing them coming out of the woodwork yet again does not inspire confidence. No, it's not proof that we're in a bubble. But it takes some heroic naivete to see that behavior and not think, "Hmm, now where have I seen people acting like this before?"
A compelling counter-argument to the assertion that people are overvaluing tech would be a clear explanation of why the prices being spent on tech companies now are justified by compelling reasons to believe that those companies can produce value for shareholders by either delivering a portion of profits to the owner's pockets or by increasing the fundamental value of the company. This explanation would of course need to be finished off by a case for why the amount of value that can be delivered to shareholders is in proportion to price at which those shares are trading hands.
On the other hand, folks churning out lists of reasons why "this time it's different" that are peppered with buzzwords like 'transformative', but never getting around to directly addressing the actual question at hand in any sort of articulate manner, have been something of a mascot for the past few market bubbles. Consequently, seeing them coming out of the woodwork yet again does not inspire confidence. No, it's not proof that we're in a bubble. But it takes some heroic naivete to see that behavior and not think, "Hmm, now where have I seen people acting like this before?"