Honestly you really have to understand the reality of Bitcoin and the concept of Satoshi plans for the creation of Bitcoin, Bitcoin should be seen as an alternative currency that is meant to work  hand in hand with other currency, Bitcoin is not created to replace or fight against Fiat currency, Bitcoin gives us the total control of our money, you need to understand that not every one is ever going to adopt Bitcoin, perhaps have you thought of those people who doesn't have access to the Internet, so you see there are reasons why we still need our Fiat.