What A Dragon Should Do.

On the other hand, some other demon gods want to take advantage of the situation to make the Tyrant Realm lose the realm war. 

This is mostly because they know that the demon god who contributes the most to causing the defeat of the realm will be rewarded with the last energy of the abyss and be able to evolve into a world-ender as the abyss is destroyed. 

But there are other reasons why demon gods chose this option, even though they knew that only one demon god could gain this reward. This is because they hate the Tyrants too much to bear helping them. 

The Tyrants didn't get their name by being generally lovely. They invaded the divine plane and wiped out the gods. They enslaved the whole realm and made people wail in anguish.