The dot-com bubble burst of 2000 was 25 years ago, and that did ruin the whole internet for years, and it was caused by the stupidity of VC investment - more or less the same as the AI bubble is now. I have no doubt that the AI bubble will crash too, it's currently being propped up by the same magical thinking.
20-ish for sure. Facebook was really the big turning point imo
But maybe that's just splitting hairs