While the power itself isn’t what changed Hell Joe, it’s still true that power isn’t necessarily going to solve human’s issues. Someone with the noblest intentions can still end up going bad in the wrong situation with power. Just look at Jahad.
From what the God of Guardians said, Jahad had noble intentions and was given training from him. But now with the 10 families and everything in the tower it’s clear to see he no longer could be called a good effect on the tower.
I also wonder about Karaka here. Wangnan and him are brothers probably. One is weak and one has power. Wangnan, the weak one, is the better person from what we know. And I do wonder if Karaka was born with his power or if maybe he was like Wangnan but was somehow able to acquire great power like Hell Joe.