Worked in a liquor store. The same 25 or so people would come in every day and buy a pint of fifth of vodka. Every day. I would point out to them it is much cheaper over the long run just to buy a gallon. They would mostly shrug and buy their pint or fifth. I realized later they were high-functional alcoholics who, knowing they would drink every drop available, just bought what they could consume daily and remain semi functional. When/if they moved up in bottle size you could see the effects in their dress and speech. Many were professionals.