Imagine two men. One of them is an honest, lawful and ethical person. However, nobody notices and his actions are not appreciated by society. So he's treated like an outlaw.
The other man is a cunning criminal who manages to make his actions appear like good deeds. He's treated like a king.
Which one of them lives the happier life? As an alternative question: Why should I behave ethically when nobody takes notice and I'm not struggling with a guilty conscience? (I'm aiming at the benefit for the individual here, not at the common good for a society.) Is ethical behaviour itself a good thing or do we only behave ethically for the sake of the consequences?