I've grown to hate the term 'functioning alcoholic'. I have abused alcohol most of my adult life (I am retired now). I teetered on the edge of making a mess of things for years, had days off due to hangovers, had the shakes at meetings in the morning and a head full of anxiety as I went about my work and my life. I really do not know how I managed to cope and actually do pretty well at my chosen career. I do know I had a miserable and unhappy time of it much of the time and that somehow that few hours of respite from hell every evening kept me hooked and coming back for more. It was and is a terrible trap that saps your life away.
Functioning? Well maybe. Alcoholic, certainly. Miserable - absolutely! Wasting one's life - so very very sadly - true.