I suffered from Osgood–Schlatter disease when I was in high school and recovered and have not had problems with it yet. Does that not make it a disease because I did not die from it?
Here's a definition for you:
1. A pathological condition of a part, organ, or system of an organism resulting from various causes, such as infection, genetic defect, or environmental stress, and characterized by an identifiable group of signs or symptoms.
2. A condition or tendency, as of society, regarded as abnormal and harmful.
(Medicine / Pathology) any impairment of normal physiological function affecting all or part of an organism, esp a specific pathological change caused by infection, stress, etc., producing characteristic symptoms; illness or sickness in general
Alcoholism is a disease. There are genetic pre-dispositions, habitual actions, and physiological changes that occur to those affected.