The movie all the way was good but the only thing I was disappointed in was when Kang San didn't become King. The worst part was that his grandmother was the one who did it. At least she should have supported him to be king. I mean, the only person who has the right to be king was him as he had survived for that. Yu Ha on the other hand would have make a good advisor as he is the one with the brains.
In the end, all the sacfrices that those people made were in vain, most especially Si Yoel's. He lived a miserable life just so Kang San could be king one day.
Even if he doesn't have to be king in the end, only he had the right to reject and not others do so for him.
Even though he agreed with them and it's all for drama in the end, but the fact that he was adamant to leave the palace and that too without seeing his grandmother is proof enough that he regretted having started it all.