No, that just makes them knowledgeable about current events. The fact that they created a bubble in the first place makes them irrational. BTW, this phenomenon isn't merely limited to things we typically regard as "bubbles." Take the following example: Which of the following industry portfolios of stocks do you think will have the highest rate of return over the next decade? A) Biotechnology, health care, and pharmaceuticals; B) Computer software, information technology, and nanotechnology; C) Grocery stores, tobacco, and confectionery.
Most people would pick either A or B, because they sound sexy. But the historical evidence would strongly suggest that the correct answer is C. Why? Because whenever people think that a company is doing something innovative, they bid up the stock price to ridiculously high levels, which lowers the rate of return. The un-sexy cash cows, on the other hand, are often overlooked. Historically, stocks with a low P/E ratio have performed the best. If people were rational, there would be no correlation between P/E and rate of return because the market would rationally settle on the "correct" price.