the internet boom (and I mean boom not bubble) started to flicker in 94, gathered steam in 95, and really got going by 96. Saying that was the time to bail out, before 97 98 or 99? I would not say that Greenspan "called" it.

bubbles are caused by collective overinvestment; that means that a lot of the ideas can be good ideas: if everybody else also doesn't invest in them at the same time. It's a bit of tragedy of the commons, it's the collective knowledge that's lacking in individual decisions.

The bottom in 02 was barely below the end of 96. It was only a bubble because it kept raising very fast for three more years.