Overcoming or not overcoming the mental obstacle usually seals their fate. You would probably be surprised at the percentage of the population who wouldn't even attempt the trek even if it was only a 60 mile multi day hike, they would give up there and then and sit it out hoping for rescue even if it meant slowly starving to death. The reality is that the soft and flabby modern Homo Urbanus have basically forgotten how to walk anything more than a mile or two.