He’s tempted by power, which helps justify his blindness and arrogance. Basically, his greed and ego are telling him what he wants to hear, and since he believes he’s the right man to lead the country, any thoughts that encourage him must be right, too. Therefore, questioning or doubting oneself must be wrong.

Plus, he’s shown that he has a natural disdain and lack of respect for people, so he constantly underestimates others.