I don't think Krakauer was trying to completely discount this idea. Krakauer was pretty clear about the fact that Chris entered the Alaskan wilderness unprepared and under experienced. Krakauer spends a lot of time juxtaposing Chris's hero worship of writers like Thoreau and Emerson with the realities of living in the wild. I think that Krakauer was trying to say there was more to Chris McCandless than his ill-fated trip into the Alaskan wildernedd. Chris had personality traits, counter-cultural or otherwise, that we could all learn from.
