It's been over a decade since I read the book and saw the film, so what I am about to say may be a product of my imperfect memory rather than the reality of the book and movie, but here goes anyway:
I see how you got the impression that McCandless was trapped in his own risk-addicted thinking from the movie, but I think that impression is editorializing on the part of the filmmakers.
I'm a rock climber and it's my experience that the risk taking in rock climbing isn't a death wish. On the contrary, it's a life-wish, a desire to experience life to its fullest even if that means risking your life. You will die--risking death is not a risk. The greatest risk you take is dying without achieving your deepest desires and dreams.
This is a pretty common view in the rock climbing community, and I think that Jon Krakauer, a mountaineer the author of the In To the Wild book, probably held a view of risk similar to my own, which is why the book presents a much more sympathetic view of McCandless' risk-taking.