I don't see "why" as a useful question when dealing with addiction. We drink because what started as a choice has affected the way we think and feel. I got trapped in the vicious cycle and continued to seek removal of pain though the use of chemicals even though at some level I grew in our awareness that it makes things worse.
I think the first of the 12 steps in important. I too think of the first three steps as a process of willingly surrendering and giving over to whatever else there is that is not oneself.
In my mind I willingly jumped out of the alcohol plane without a parachute, and there was no going back. At the time I did not have any faith. Despite the dire predictions of those on the plane I have not hit the ground yet and have found I can fly on my own.