It is saddening that this argument is used even on HN. That's equivalent to the old "You don't need privacy if you got nothing to hide". Examples as in Cyprus [1] prove that you should always be careful when trusting banks or any centralized system. Your line of argument is very common among representatives of banks, governments or people who are simply uneducated on the subject. Or a combination thereof.
http://www.businessinsider.com/r-amid-fears-of-greek-control...