A reason doesn't mean from a rational perspective. A reason someone wouldn't go in an elevator might be an irrational fear of heights. A few reasons someone might continue drinking even though its slowly destroying their lives and relationships:

* Undealt with trauma/abuse

* Lack of skills to express themselves emotionally, and experience that it is a "socially acceptable outlet" (for a while)

* Depression and lack of self worth (sometimes brought on by excess drinking, in a cycle/loop)

* Neurochemical or biological imbalance - note that the rates of ASD spectrum or bipolar alcoholism is much higher than neurotypical, for example

* Cultural enforcement of drinking (frequently being around people with other of these issues)

* Others

Or most frequently

* Multiple of above