Which detail from "to build a fire" best supports the idea that survival was not guaranteed along the actual yukon trail?

The part in the story which tells that survival was not guaranteed is the signage or the warning of the old-timer that says "It is too cold to travel ". This warning was ignored by the newcomer thus making himself crossed to the place of death. When ice is too dense and he's freezing he could not make a new fire and at the end of the story he died.