This is only so because fiat money is still the major and most efficient means of exchange for goods and services but as time goes by and bitcoins becomes more popular then you will find that fiat (physical money) will become less popular as people will gravitate towards a cashless, fast, system that eliminates the need for them to leave the comfort of their home to do any transaction whatsoever. This will happen on the fast, secure un hackable blockchain system which most companies are adopting now.