Why did the man go a different way in "To Build a Fire"?
The man is a newcomer to the Yukon Territory, he is smug and rejects the advice that he is given by experienced men from the Canadian wilderness. He thinks that his journey, on foot will be easy and without incident.
"He is on his way to join the rest of his companions at an old mining camp on a distant fork of Henderson Creek, and he estimates his arrival time will be six o’clock in the evening. The man is traveling on foot; all he has by way of supplies is his lunch."
Its not that he goes a different way, but that he underestimates the severe cold and what supplies and provisions that he should take with him to help him survive the journey. He misunderstands the threat of being in the frigid cold and how it could affect him.
In fact, he learns very quickly, how threatening the cold can be, first to his feet, after he gets them wet, and then to the realization that he will die in the cold wilderness without a fire or shelter.