Everyone is different, in so many ways. I used to wonder why my sister was devoured so quickly by alcoholism, dead at 38 from cirrhosis, while I had been abusing alcohol for more than 3 decades. For some things, there isn’t an answer, and this is one. Be glad that you have been dealt the softer side of addiction but realize that your sister’s dilemma could very well be yours one day, if you chose to ignore the addiction. Use your consciousness of the reality of the addiction to pull yourself out of its grasp and be there for your sister, with compassion and love.
For the record, my sister had everything externally imaginable, looks, family, big house, cars and all the trimmings. She started drinking in her early 30s and it literally destroyed her. It can happen to anyone, alcoholism doesn’t discriminate. IMO, alcoholism is a disease that first attacks the brain and then distorts identity; a disconnection from the conscious or spiritual self and higher power. For me, recovery is the process of rediscovering myself by listening to my heart instead of acting on thoughts or impulses.
You have been given the gift of awareness and the desire to save yourself from a life of despair. I don’t know your story but you found SR for a reason. Use the resources that you have been given to change your life and change your world!