How come you make a conclusion that we are in a bubble,only using this comparison?
I don`t understand your theory.Bitcoin can`t be compared with cash in circulation,because most of the bitcoins aren`t in circulation.Most of the btc are owned by HODLers ,who refuse to use them and only wait for the price increase ,when they sell them for USD to take the profit.You have to compare BTC in circulation with USD in circulation.