Chris McCandless was a bold man.  He rebelled against the typical lifestyle that we all call "normal" and "right".  Whether the actual cause was from lunacy or something else, nobody will ever truely know.  But there is good evidence that this was not just an outburst of craziness.  This could be seen as an act of foolishness, but to me, it was not.  This was an adventure to find purpose in life and escape the world.
  By going into the wilderness, I don't believe that Chris would have changed completely.  I believe it was just a very long escape.  I do in some ways think he would have returned home and maybe picked up life where he left off.  No one will really know how this would have affected his life due to his unfortunate death.
  I think what Chris did was his way of "sticking it to the world."  He wanted to just focus on living for himself by himself.  Chris fulfilled his goals in the end, but was unable to return to the normal society.  Maybe this was for his own good and for good reason.