You believe you "have seen it all" Reality is that you only know your personal experience, you're ignoring genetics essentially https://medicine.wustl.edu/news/alcohol-dependence-psychiatric-disorders-share-genetic-links/ >>An international team of researchers has identified a gene that regulates how quickly the body metabolizes alcohol as a key risk factor for alcohol dependence. The researchers, from Washington University School of Medicine in St. Louis and several other institutions, also linked genetic factors associated with alcohol dependence to other psychiatric disorders.