Pardon me for asking a dumb question. Perhaps someone will have a smart answer that will enlighten the list. In the US today, there are two obvious bubbles.
Cost of production is less than a dollar.
Active traders believe that the prices are ridiculous, but continue to participate. Their basis is the greater fool theory. Among the traders, gains and losses are zero sum, therefore no net social cost. Probably not a big deal. Billion dollar internet stocks mostly reflect a thin float and, again, the greater fool theory.