Question

Why do we dream? If we do not se dream what will happen?

Answer 1

Dreams happen because of stresses, or even because of exciting or new things happening in your life. It means you don't remember them, I assume you are asking about dreams in sleep not related to life goals :) The thing is our subconscious brain is the driver of our dreams and our conscious brain is at rest in sleep.

Answer 2

Dream is nothing but that probability that can de happen if we do
If we didn't see dream we will be a little confused about what will happen next to us