Strangely enough, both my stepmother and another set of unrelated close friends of my family were close with McCandless's parents. From what I've learned from them I've come to believe that Chris was dealing on some level with the realisation that his comforts, and his parents' comforts were built on their close ties with a zero-sum military establishment and its attendant (highly profitable) technology. The blunt realisation of what that actually means has driven stronger personalities than Chris' into madness. I think Chris was primarily eminently sane, if over-endowed with the romanticism of youth and words, but he died before he could understand the vast web of murder that binds and divides us all, and was unable to forgive his father until the very end.