(Bloomberg Gadfly) -- There is no official measurement. In that run, it has added roughly $90 billion in value, crossing above $100 billion for the first time on Friday before dropping back a bit.

It's only a matter of time before it becomes a permanent member of the $100 billion club. Bitcoin is now worth more than a number of financial firms that would be its rivals, like American Express Co. ($81 billion)Still, compared with other asset classes, like real estate or stocks, bitcoin is a pimple, which is why some people have convinced themselves that bitcoin can't be in a bubble.

New York City real estate alone is worth more than $1 trillion. There is $8 trillion worth of gold in the world, nearly $15 trillion in Treasury bonds and more than $25 trillion in the US stock market. Bitcoin's mere $100 billion, by comparison, is small.