Calloused to the Word of God

This is terrifying.  How does a man turn into a mere hearer?  After all, he listens to the same word as the doer.  He sits in the same church building, sees the same preacher, hears the same preaching, and might even take the same notes.  He hears the points, the applications, the exhortations, and yet, he is a mere hearer; he does not do what the Word of God says.  Why?  Or rather, how?