Bubble or not?

Web 2.0, actually, I think it is a bubble, but the cause is quite different from the last one in 2000. In 2000, the bubble results from excessive investment in uncertain revenue model, and uncertain technology. But this one results from, my opinion, uncertain market, and uncertain customer behaviors. We all know that one way to survive is to make money from advertisement. But how many can do this? Besides, the unfamiliar huge market like China, lots of investors don't understand the customers there as well as they don't understand the different business way.

That's why bubbles happen this time.