I don’t think the end result is identical. If you take B, you now have evidence that, if a similar situation arises again, you won’t have to experience excruciating pain. Your past actions and decisions are relevant evidence of future actions and decisions. If you take drug A, your chance of experiencing excruciating pain at some point in the future goes up (at least your subjective estimation of the probability should probably go up at least a bit.) I would pay a dollar to lower my best rational estimate of the chance of something like that happening to me—wouldn’t you?
I don’t think the end result is identical. If you take B, you now have evidence that, if a similar situation arises again, you won’t have to experience excruciating pain. Your past actions and decisions are relevant evidence of future actions and decisions. If you take drug A, your chance of experiencing excruciating pain at some point in the future goes up (at least your subjective estimation of the probability should probably go up at least a bit.) I would pay a dollar to lower my best rational estimate of the chance of something like that happening to me—wouldn’t you?