Stopping drinking is a whole process. Its stages appear to be the following:
1 Excessive drinking over a protracted period
2 The individual moves from denial to acknowledgement that the drinking is excessive
3 The individual acquires the desire and will to moderate
4 The individual attempts to moderate but fails due to the physical craving
5 The individual recognises that moderation is impossible
6 The individual acquires the desire and will to stop altogether
7 The individual attempts to stop altogether but fails within hours or days
8 [This is because the physical craving persists for some time after the last drink]
9 The individual recognises that stopping is impossible without help
10 The individual acquires the desire and will to seek help
11 The individual detoxes with (a) the practical help of other people (b) home detox (c) medical detox (d) medical rehabilitation
12 The individual is now properly detoxed: the job of stopping drinking is now complete and the new job is 'do not start again'.
1 can last a very long time. 2 is a gift. 3 is a gift. 4 is down to the individual (but very tough in the circumstances). 5 is a gift. 6 is a gift. 7 is down to the individual (but very tough in the circumstances). The operation of 8 is out of the individual's hands. 9 is a gift. 10 is a gift. 11 requires the right people to be in place and also requires the individual to recognise who those people are. 12 also requires a recognition of this fact and the will to do something about it.
This, for me, goes a long way to explaining why, when people start again, they usually do not stop, or they stop only after far longer than one would expect.