The subconscious is IMO, the much larger part of the mind that possesses the enormous inherent genius, and feeds the most pressing data to the much weaker conscious part.

It is constantly aware of everything in your surroundings, past, present...possible futures.

Your unconscious is already aware, but until you finish this sentence you will not be consciously aware of the sensation of your little toe on your left foot.

You may not believe in it.....but for all practical purposes, the unconscious exists....
I may not believe that my hand exists, but I can pick up a pen..So it's safe to behave as though it is really there...because the evidence would strongly suggest so.

Hypnosis works mainly on this understanding.....Without belief in the things outside of our awareness, you will not be able to hypnotise effectively.
It's the same as playing football without the belief that the ball exists....You can be as philosophical as you like about it....but for the purposes of the game, you will do better if you assume it is there and kick it