Is alcohol usually the culprit for someone having to get a liver transplant? How survivable is a liver transplant?

My 56 year old uncle had a liver transplant back in June of 2018. I heard that he was an alcoholic and that he drank a lot of alcohol since the late 1980s. Why do Americans like to drink alcohol? Unfortunately, my uncle's liver is not functioning well so he may need another transplant to live. My family was informed by the doctor that my uncle likely does not have much time to live and that he may die within 6 months to at most 5 years. He has consumed more alcohol since he had his transplant and also stopped taking his medications shortly before Christmas 2020. It is now January 16, 2021. Sadly, my aunt is another alcoholic who has been lucky to not need a new liver but she does not help to keep my uncle away from alcohol. Do you guys think my uncle will die or is the doctor just trying to scare my family? Do you think my uncle has a chance of living until at least age 80? Also what is so good about alcohol and why would someone who got a liver transplant would want to drink alcohol if getting a liver transplant is a painful and uncomfortable process? My uncle could not walk for at least a month following the surgery and could not drive for 5 months.