To be honest, Ji Changsheng had anticipated that the spark of Ying Country could possibly deteriorate.
The tale of dragon slaying warriors turning into evil dragons has been occurring since ancient times across the universe. What makes Ying Country any exception?
But even with anticipation, seeing it actually unfold stirred some uncontrollable killing intent within Ji Changsheng, regardless of how disadvantageous this was for him.
Because he's cultivating merit.
If he goes on a killing spree during the meritorious spark, even if the once dragon slaying hero has now turned into an evil dragon, Ji Changsheng suspected he would end up losing more than he gained.
After all, the dragon slaying heroics back then were real, and the hero was genuinely heroic. The subsequent evil doings would not cover up the goodness from before.