Add to that the need to expand the supply of equivalent-value-BTC IOUs if private BTC-denominated debts collapse in value for whatever reason (eg '08 financial crash). When AAA-rated securities evaporate, the repo operations that rely upon those securities to provide almost all the liquidity in the financial market are kaput. Hard to replicate that with BTC. A BTC-based world needs to address ALL the reasons the USD is used not just appeal to those who see hyperinflation lurking around every corner