There could be many possible answers but to answer this question on by and large scale we need to know the difference of an the ideology between Arjuna and Duryodhana as being a predominant characters from either sides i. Pandavas and Kauravas respectively.
Srimad Bhagavad Gita is all about Arjuna asking questions to Lord Krishna and Lord Krishna clearing his doubts.Both Duryodhana and Arjuna had doubts about life.The Mahabharata war in Kurukshetra could be avoided, if Lord Krishna had told Bhagavad Gita to Duryodhana instead of Arjuna.But Lord Krishna didn’t tell Bhagavad Gita to Duryodhana,why?
Duryodhana’s arrogance and ego prevent him from asking questions and clearing his doubts.On the other hand, Arjuna is not hesitant nor he thinks that he knows everything. Arjuna surrenders himself to Lord Krishna and asks questions after questions.Answers will only come to those who asks questions.
We need to know what happened when Krishna tried to persuade Duryodhana.But whenever Lord Krishna tried to persuade Duryodhana to avoid war the arrogance and ego of the Kauravas, especially Duryodhana that destroys all the possibilities of averting the war.While Lord Krishna was trying to convinience Duryodhana for compromise or settlement ,Duryoghana had replied with arrogance ,”I know what is right and what is wrong. You need not tell me. My problem is that instead of knowing what is right, I don’t feel like doing it. I know what is wrong but I can’t stop myself from doing it.”
I would like to recall Mikhail Gorbachev’s words,”Sometimes it’s difficult to accept, to recognise one’s own mistakes, but one must do it. I was guilty of overconfidence and arrogance, and I was punished for that.”