It seems that no one has mentioned that the effect of relative wealth might be severe also from a rationality point of view. In a more primitive environment, if

It seems that no one has mentioned that the effect of relative wealth might be severe also from a rationality point of view. In a more primitive environment, if your neighbor becomes too powerful, he might enslave or even kill you, so better keep him in his place. Similarly, if you take the $100 and are silent, and protect the killer, you risk severe punishment if you are caught. Even if I agree that the decision is made based on moral conscience for most people rather than economic calculation (which might be the case for sociopaths), there is a rational basis for this. Fundamentally, to make sure that I don't get murdered myself by the murderer later, I better not comply with him, as he is proven to be ruthless. In addition, because other people are moral beings as well, $100 is a very small compensation for risking jail and being shunned for the rest of your life, a very bad economic decision.