Supposing that alcoholism is a disease then why are people mad at alcoholics?

Good question: One - because many people give lip service to the disease concept, but believe in their heart of hearts that this individual is making a choice, and it is a bad choice. Alcoholics' behaviors affect and hurt ones they love and care about, and this makes people angry - they take it personally. "if you really loved (or cared about) me, you wouldn't drink like that!" family therapy is important.