Agreed. And don't forget, YY killed Yunalesca, his own daughter and heir. But it was not a conscious YY. The kid fayth said this new "spider YY" is somehow a being that lives only to summon.

To me it is a tragic story: He got cocky, used way too much magic/ power and got overwhelmed by it, leaving mindless beings (Sin, his spider self) bent on destruction loose on his world.