Throughout "To Build a Fire," the man exhibits quite a bit of pride in his abilities, and this sense of pride is connected to his sense of being a Man with a capital M. Ultimately, the man seems to do everything in his power to make his journey successful, but his fatal mistake has been made before he even began his journey. He didn't heed the old-timer's advice, and decided to travel in temperatures lower than fifty degrees below zero without a traveling partner. It's a bad call, to be sure, but it's also just plain old hubris.
In having the man criticize the old-timer for being too "womanish," Jack London draws a direct link between the man's death and his need to feel masculine.
The story ultimately suggests that human pride cannot compete with the cold and brutal indifference of nature.