A 'want' to be sober is definitly needed, as mentioned pople kill themselves drinking, though to have a 'want' you need to see a 'benefit', I guess how marketing works, there is no point in selling something in an advert if people don't see any 'benefit' to themselves.
For me it was health reasons, my body was starting to have issues and so the 'benefit' was living into old age, and still enjoying everything life still has to offer!