All due respect, but I think that's retrospective bias talking. It feels obvious in hindsight that it was a bubble, so those conversations with bearish people are amplified in your memory. The fact that some bears existed proves nothing; no matter what is going on in the macro-economy, at any time in the last 20 years Nouriel Roubini et al. would have been happy to explain how it's all an illusion, we'll all be eating out of trashcans in two years, just you wait.

While the music was playing in the late '90's, the cautionary voices weren't any louder, or taken any more seriously, than they were at any other time. They weren't even all particularly focused on the Internet boom; much, much more pessimistic sentiment at the time was focused on Russia's sovereign debt default, the currency crisis in Asia, or the LTCM bail-out.

As for the Internet stock valuations at the time, many people reasoned that if you looked at the entire investment in "new economy" companies, all that was required for those investments to reward their holders' level of risk was one Microsoft. This was essentially true, by the way, and if you stuck to your guns and held onto Amazon from its local peak on 3/31/1999 ($86) you would be up about 120% today ($188).

It's pretty easy for me to sanity check - I sold a large block of YHOO in '99 because I was convinced it was strongly over valued, several friends congratulated me on my wisdom. Of course I spent over a year feeling like an idiot, but it does make for a clear memory.