In fact, if one looked back at what Arthas had experienced since he was a child, they would find that Uther the Lightbringer was actually partly responsible for Arthas's final fall into depravation.
Uther was a powerful paladin with a pious and firm faith in the Holy Light, but he was not a good teacher.
In fact, his devotion to the Holy Light made him a little pedantic. He didn't understand that there was a difference between religion and royal power many times.
As the crown prince of Lordaeron, although Arthas was brave and tenacious, he also had the arrogance and impulsiveness of a young man. Because he had had high hopes placed on him since he was young, the responsibilities and obligations of the crown prince were pressuring him as he grew older. This made him doubt whether he could lead the people of Lordaeron like his father.
