Overconfidence often follows from blurring the lines between fact and faction, between what I desire and what is real or available to me. Between mistaking activity for progress, and elevating what we say, think or feel to the same status as that which we actually do. It's a kind of self-deception of convenience that only superficially protects us from unwanted truths about ourselves; a defense that fails because playing make-believe only produces more stress and strain.
The distorted thinking we inherit from the way we drink and from what we think and do while we're drinking does not disappear by virtue of our putting down the drink, even though it's very seductive to believe that this is the case.
Everything takes time. And work. Attention must be paid.