I think someone saying, "come on, burst already" does not see the bubble popping as "when diminishing confidence in AI has reached all bits of the economy" because they see it as something likely to happen soon, and that ain't happening soon. However, we may see reduced AI investment from some quarters soon.
It's also worth recalling that stock market bubbles can and do pop very suddenly - I don't think it's that reasonable to take a definition that spreads it out over months, but maybe that's what you're saying.