They had existed for such a long time, thinking it was enough to simply let their entire race live more peacefully, maintaining a simple existence to reduce conflicts. However, this mindset was fundamentally flawed since they were essentially a race above others. Although classified as part of the Demon Race, they were living beings that had to exist in a community. The approach they had taken was entirely wrong.
The current situation had filled them with immense sorrow. If they had a precise method from the start, perhaps they wouldn't be ruling the entire world now, but at least they could have safeguarded their culture without it being tarnished. That would have been a significant achievement.