Within the context of the story (which I didn't have the time to more than merely synopsize), it is made clear that he is indeed a fool - not merely for hiking in the Yukon alone, but for disregarding the "Golden Rule" of all the old Sourdoughs that no man may venture forth alone when the temperature drops to below -40 °F.
London drops other clues that make it clear that the man is entirely culpable for his obstinate refusal to think ahead, or be reasonable.
Regards,
I read it in class...likely 5th grade ...1967/68
admit I don’t recall the nuance that precise