Many have criticized Chris McCandless for being foolhardy and unprepared for his sojourn in the Alaskan wilderness. The subject would not have been so hotly debated where there was not truth in that claim.
However, as Krakauer states openly in his book, he identifies with and is sympathetic to Chris. He builds a strong case that while Chris did make some risky moves, it was bad luck more than his own foolishness that did him in.
One point Krakauer makes is that Chris deliberately refused to take too many precautions. Yes, he could have gone out in a Winnebago armed with every safety device and precaution known to humankind and stacks upon stacks of food, but that would have defeated Chris's purpose. Chris wanted to test himself and face nature as simply as possible to see how well he would do surviving with the bare minimum. For example, while he was much criticized for not taking him the map that could have led him to safety, his desire wasn't to know where everything was: at that point, it would become a camping trip and not a genuine attempt to face living alone in the wilds. This was a courageous venture because it carried with the possibility of dying.
Chris researched what he was doing and came with what he thought he needed to survive, if no more. He took a gun and he took some food. He did make mistakes, such as with the antelope he killed, but he was not simply rushing like a greenhorn into the middle of the Alaskan wilderness with no knowledge or interest in survival techniques.
It is easy, as Krakauer points out when he describes his own youthful death-defying adventure climbing a mountain, to point the finger of blame at people who die in the wilderness, but often there is a thin line between success and failure; if you are going to take a genuine risk, as Chris did, it's impossible to be prepared for every possibility.