First off, the narrator is engrossed with the man's vulture eye, declared that "one of his eyes resembled that of a vulture--a pale blue eye, with a film over it. Whenever it fell upon me, my blood ran cold". The narrator tells us that there was no strong emotion in their strategy to rid thereself of the old man's evil eye neither did they didn't want any of the old man's money; the man had "never wronged him". This conflict is simply created due to the old man's eye that distressed the narrator and made him feel uneasy,
so he had to be rid of it. The reason it is the main conflict is due to the fact that the conflict is resolved by the end of the story.