Doesn't this theory also apply to a stock traded on a stock market?

edit: reading the wiki article, I see that it indeed can. The assumption being that there is no rational justification for the price paid.

However, this assumption is wrong. Simple calculations give a price much higher than the current value if Bitcoin comes into widespread use as a currency. In more detail, given the limited supply and any arbitrary transaction volume, you can come up with a price for Bitcoin. The current valuation is not supported by the transaction volume. However, low estimates of transaction volume if Bitcoin comes into widespread use imply a much higher price.