It's quite
simple, really: if you don't get
caught, no one will know that you've done anything
wrong. If you're really
lucky, or really
good, no one will ever even realize that a
crime has been committed, and then (if you take a
subjective,
postmodernist view of
reality) it's almost as if
nothing ever
happened at all. Except, presumably, for some
net benefit to
yourself.
Consider: people are only punished by society if they get caught doing something "wrong". There is the possibility that they will punish themselves with a guilty conscience, but people most often have some means of justifying their actions ("I needed the money more than he did" or "He was a fucking Commie!"). If society doesn't catch you, you haven't committed a crime -- the beauty of being innocent until proven guilty.
Not that I'm advocating any of this, of course -- it's just a sociological observation.