When asked about their preferences verbally, most people wouldn't endorse the extreme time discounting that would justify eating the marshmallow right away, and wouldn't endorse killing a test subject to please the experimenter. So I don't think these behaviors can be viewed as rational.
You are aware of the difference between expressed preferences and revealed preferences, yes? It doesn't seem to me that sticking with expressed preferences has much to do with rationality.
If it's worth saying, but not worth its own post, then it goes here.
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