what did Chris McCandless do to cause pain to his family?

I really like this novel but I always found Chris MCandless to be a rather unsympathetic character. In his quest to become a "free spirit" he forsakes his family. He, in fact, puts them through hell. Chris disappears in his senior year of university. He leaves no clue as to where he is going or exactly what his intentions are. Despite pleading letters, Chris never makes an attempt to relieve their anxiety. Where is he? Is he alive or dead? Chris does make some contact with his sister, who he was closer to, but his whereabouts and intentions are cryptic. Chris turns his back on his parents because they represent (to him) a lifestyle that is hypocritical, self-serving and suffocating. Despite Chris's likable personality he dies in a similar way.