And if existence is only our consciousness, then how can we hold anyone at fault for any misdeed, since it is only our consciousness (which we can change)?
Vasubandhu, the Consciousness-Only sage, said that the world is like a dream. When we are dreaming, we do not realize that we are dreaming.
We all collectively create the world through our thoughts, so any one of us cannot change the world just by our individual thoughts. It is accumulated from all of our consciousness.