The biggest problem is that right now the financial infrastructure that exists to handle transactions for other things doesn't quite exist for bitcoin. If you send your money to a bitcoin exchange, how do you know that people won't run away with it?
This is impossible to know. But how is that different from Fiat? If you are sending a prepayment to the Bank card you have confidence that the person to whom you have sent the translation will not run away with your money? Scammers will use any methods to take control of your money. The only way to protect is to not use unverified websites and services.