What evidence from "To Build a Fire" might lead you to this inference? The man is too confident.
A. Empty as the man's mind was of thoughts, he was keenly
observant, and he noticed the changes in the creek, the curves
and bends and timber-jams, and always he sharply noted where
he placed his feet
B. As for lunch, he pressed his hand against the protruding bundle
under his jacket. It was also under his shirt, wrapped up in a
handkerchief and lying against the naked skin. It was the only way
to keep the biscuits from freezing.
C. He looked at his watch. was ten o'clock. He was making four
miles an hour, and he calculated that he would arrive at the forks
at half-past twelve. He decided to celebrate that event by eating
his lunch there.
D. The old-timer had been very serious in laying down the law that no
man must travel alone in the Klondike after fifty below. Well, here
he was; he had had the accident; he was alone; and he had saved
himself. Those old-timers were rather womanish, some of them,
he thought.