There are few valid reasons why the world need virtual currencies like bitcoin.
1. Bitcoin was introduce to us because when US economy went down all other countries jobs and currencies are affected.
2. Virtual currencies arent affected by fiat so even if a certain fiat currency is down our virtual currency (bitcoin) is not affected.
3. Virtual currency like bitcoin has no tax which the government are required for us to pay.
4. You can do fast transaction without the hassle of giving a certain person or company to much information about you.