A mugger is less likely to be deterred by fear of punishments. It usually comes from desperation and impulsiveness, it's not like they've carefully weighed their chances of being caught. SBF probably thought "If I get away with this I get a billion dollars and if I don't I just get a slap on the wrist and go back to normal life".

I think not letting anger factor into it is good, but we also have to make sure the deterrence is there to prevent the inevitable future SBF.