Not wanting to believe is different from not believing. Not wanting to believe requires active work to avoid believing "accidentally". Why would anyone, why would I, actively invest in not believing in my own worth? What purpose does it serve to believe that I am not good enough (yet)?
After my last coaching call, a friend shared this article with a reminder about Renée Brown's book "Rising Strong". Basically, the story you make up in your mind in the absence of information is not necessarily the full truth. And given that our minds are much more creative around detecting fear, you are more likely to make up a horror story than a beautiful happy ending.