My last post mentioned in passing that the puzzle of the self-torturer may be complicated by the fact that money has diminishing marginal value. This can mean that a few increments (of pain for $$) may be worth taking even if a larger number of such increments, on average, are not. So to make the underlying issues clearer, let us consider a case that does not involve money.
Suppose ST is equipped with a self-torturing device that functions as follows. Once per day, he may (permanently) increase the dial by one notch, which will have two effects: (i) marginally increasing the level of chronic pain he feels for the rest of his life, and (ii) giving an immediate (but temporary) boost of euphoric pleasure. Before it is permanently attached, ST is allowed to play around with the dials to become informed about what it is like at various levels. He realizes that after 1000 increments, the burst of pleasure is fully cancelled out by the heightened level of chronic pain he would then be feeling. So he definitely wants to stop before then. (We may assume that he will live on for several years after this point.) Is it rational for ST to turn the dial at all?
Surely not. Each increment imposes +x lifetime pain in return for a temporary boost of y pleasure. We may treat these as being of constant value (bracketing any slight differences in, e.g., the duration of ST's subsequent "lifetime" between the first day and the thousandth -- we could make it so that the pain only starts on the 1000th day if necessary). And we know that it would be terrible for ST to endure 1000 increments. That is, the disvalue of +1000x lifetime pain vastly outweighs the value of 1000 shorts bursts of y pleasure. Since the intrinsic values here are (more or less) constant, it follows that the intrinsic disvalue of +x lifetime pain vastly outweighs the intrinsic value of a short burst of y pleasure.
So -- assuming that there are no extrinsic values in play (e.g. we're not to imagine that ST has never experienced euphoria, such that a single burst would add a distinctive new quality to his life, or anything like that) -- it follows that each individual increment of the self-torture device is not worth it. It would be irrational for ST to turn it at all. So there is clearly no great "puzzle" or "paradox" here.
Compare this result to the original puzzle involving money. Since money has diminishing marginal value, it might be that (n times) $y is worth (n times) x pain (for some n < 1000) even if $1000y is not worth 1000x pain. That contributes to the intuitive force of the "puzzle", insofar as at least early increments seem like they might be worth taking. But it should be clear that merely adding a resource with diminishing marginal value can't really create a paradox here where there wasn't one previously. There will still be some threshold point n where it is irrational (of net intrinsic disvalue) for ST to turn the dial a single notch more.
So there is no great "puzzle" to the self-torturer.