因为迦尔纳比难敌更虔恶劣、更邪恶。难敌的叔叔沙恭尼让他憎恨般度族。沙恭尼和迦尔纳从小就充满了仇恨和邪恶。另一个原因是持国的欲望。难敌和迦尔纳在德罗纳的Gurukul成了朋友，两人都在那里接受德罗纳训练。另一个重要的一点是他们之间的年龄差异，大约在12到18岁之间。因此，如果我们将难敌的年龄视为10岁，那么Karna的年龄大约在22到28岁之间。因此，当迦尔纳遇到一个没有经验的小男孩难敌时，他是一个更有经验的年轻人。因此，在那个年龄，迦尔纳比难敌更了解非法和正法。迦尔纳从未有过像沙库尼这样的邪恶叔叔来让他的内心充满仇恨或邪恶。相反，迦尔纳受到了父母的爱和教育，我们将受到德罗纳和持斧罗摩的训练，但他仍然变得邪恶。迦尔纳嫉妒阿周那，这变成了对般度族的仇恨。阿周那的天赋伤害了迦尔纳的自尊心。因此，他在德罗纳的古鲁库尔与难敌建立了友谊。所以当我们比较难敌和迦尔纳时-难敌邪恶的原因是沙恭尼、迦尔纳和持国。但是迦尔纳之所以邪恶，是因为他自己，也就是他的嫉妒、仇恨和自我。
Because Karna was more adharmi and evil than Duryodhan.
Duryodhan was made to hate Pandavas by his uncle Shakuni. From his childhood both Shakuni and Karna filled hatred and evilness in his heart. Another reason was desires of Druthrashtra.
Duryodan and Karna became friends in Drona's Gurukul, where both were getting trained by Drona. Another important point is the age difference between them which was around 12 to 18 year's. So if we consider Duryodhan age as 10, then Karna would be around 22–28 year's old. So Karna was more experienced youth when he met a inexperienced little boy Duryodhan.
So at that age Karna was knowing more about Dharma and Adharma than Duryodhan.
Karna never had evil uncle like Shakuni to fill his heart with hatred or evilness, Instead Karna was loved and educated by his parents and we'll trained by Drona and Parashuram, but still he became evil.
Karna was jealous of Arjun, which turned into hatred towards Pandavas. Arjuns talents hurted Karna's ego. So he made friendship with Duryodan in Drona's gurukul.
So when we compare both Duryodhan and Karna-
Reasons for evilness of Duryodan was Shakuni, Karna and Druthrastra.
But
Reasons for evilness of Karna was himself, that is his jealous, hatred and ego.