Think Arthurian legend but with a twist. The entire story takes place on an island which is the last refuge of the human survivors (a limited number) after an apocalypse. The island also houses an array of various mutated creatures, some which the people hunt for their survival and some which hunt people. In this setting, I have Arthur extract the sword from the stone and people believe that he is the chosen one to lead them to salvation and follow his every word.
In this scenario, what is it, possibly, that Arthur can do to turn the people away from him, to lose faith that he would be able to liberate them ?
Here, Arthur is neither dumb nor lazy; however, he is motivated by jealousy and an abnormal desire to feel adored by each and everyone. He can't stand people praising anyone else.
There is also an adversarial tribe which is opposed to Arthur's tribe, living on the opposite side of the island.