The bullet does destroy candy bars. Unless you're introducing some sort of quantum suicide assumption, where you average only over surviving future selves? I suppose then you're correct: the argument cited by Landsburg fails, because it must be assuming somewhere that your utility function is a probability-weighted sum over future worlds.
You're right again, thanks again :-) I was indeed using a sort of quantum suicide assumption because I don't understand why I should care about losing candy bars in the worlds where I'm dead. In such worlds it makes more sense to care only about external goals like saving weasels, or not getting your relatives upset over your premature quantum suicide, etc.
Imagine you're playing Russian roulette. Case 1: a six-shooter contains four bullets, and you're asked how much you'll pay to remove one of them. Case 2: a six-shooter contains two bullets, and you're asked how much you'll pay to remove both of them. Steven Landsburg describes an argument by Richard Zeckhauser and Richard Jeffrey saying you should pay the same amount in both cases, provided that you don't have heirs and all your remaining money magically disappears when you die. What do you think?