C366 Why Did the Demon Race Betray Him?

So why did they still betray the Devil Sovereign during the Great War of Immortals and Demons? If it were simply a matter of some demons wanting to betray him, that would be quite common. But it seems that the entire populace of the Demon Realm turned against him.

Su Yinjian reflected on the Devil Sovereign's temperament. Having betrayed the Immortal World before taking refuge in the Devil Realm