your bank analogy is flawed. if someone robs a bank it does not effect the account holders because in the majority of countries banks are insured by the central institution of that country. and if its not insured then you should probably not use that bank.
The heart of this saying is that man has to make tough choices and that there is no such thing as evil. people simply percieve things differently and we all have our reasons for what we do.
the Ends and means is saying are you willing to be accountable to the inquiry of your actions after you have done them.