A discussion I have been involved with once before likened drinking to religion; it was suggested that it is human mental frailties that lead to the need in a lot of people for some kind of prop/support whether that be religion, alchohol, drugs, adrenaline sport, or a mixture. Some people are predisposed to relying on external crutches to support mental frailities. Also, boredom can play a big part in someone pouring a drink, lighting up, tucking into the chocolate.
I guess that if you are able to manage it, fine. If not, as you say, it’s the slippery slope…