The short answer to the question “why does Krakauer continue after he dry-heaves from fear” is that he had no choice. By this point in his story, Jon Krakauer was too far along on his journey, and was too geographically and emotionally isolated to turn back. Going forward was as reasonable an option as going backward. Into the Wild, however, is a little more personal than that. Christopher McCandless was always in Krakauer’s thoughts. McCandless had gone alone “into the wild” of Alaska on a solitary journey with the hopes of ‘finding himself’ while rejecting the modern comforts of life (i.e., materialism). He died, possibly of starvation, possibly, if Krakauer’s later theory is correct, from consumption of a poisonous plant. In any event, the parallels between McCandless’s fatal journey and that of Krakauer were clear. Both were driven by the intangible psychological characteristic that has driven explorers and adventurers throughout history. Reflecting on his own perilous situation, Krakauer provides the following thoughts in Chapter 14 of his book:
“I was twenty-three, a year younger than Chris McCandless when he walked into the Alaska bush. My reasoning, if one can call it that, was inflamed by the scattershot passions of youth and a literary diet overly rich in the works of Nietzsche, Kerouac, and John Menlove Edwards, the latter a deeply troubled writer and psychiatrist who, before putting an end to his life with a cyanide capsule in 1958, had been one of the preeminent British rock climbers of the day. Edwards regarded climbing as a "psycho-neurotic tendency"; he climbed not for sport but to find refuge from the inner torment that framed his existence.”
Krakeuer, in his writings on McCandless, noted the latter’s infatuation with the writings of Henry David Thoreau and Jack London (“McCandless had been infatuated with London since childhood. London's fervent condemnation of capitalist society, his glorification of the primordial world, his championing of the great unwashed—all of it mirrored McCandless's passions.”) Krakauer, of course, would live to write about his solitary journey into the icy glaciers of Alaska, and has been widely quoted as having said, “I got away with it. Chris didn’t. That’s the only difference.” The need to conquer fear and nature’s most formidable obstacles has driven innumerable mountain climbers over many years. Krakauer continued after the episode where the fear grew so intense that he vomited air because he had to survive, but also because conquering fear was one of the reasons he was there in the first place.