Why was Chris McCandless guilty of hubris when he walked into the wild unprepared for adventure?

Hubris means to be overly confident or arrogant.  Chris
McCandless demonstrated this when he entered the wild with few supplies and a sense that
he could survive in the wild.  He chose to leave his map on the dashboard of the man who
had driven him to the entrance point of the Alaskan park.  If he had the map he would
have known that there was a bridge that would allow him to cross the river so he could
make it back to civilization.

In the past he had almost
died in the desert.  He had taken off relatively unprepared and been lost.  It was
another example of his feeling hubris-tic nature.  Had he not been that way he would
probably still be alive.