The flaw with that line of thinking is that we are not robots (LaMDA and Zuck, you can stop reading now). We don't always (want to) make optimal decisions base

The flaw with that line of thinking is that we are not robots (LaMDA and Zuck, you can stop reading now). We don't always (want to) make optimal decisions based only on how objectively healthy they are, and that's perfectly fine, and not really "self-destructive" in the sense you're implying. There's an adage somewhere about living health and becoming a beautiful, healthy corpse some day. Alcohol is bad. Maybe cutting it entirely from your life will get you an average 0.56% increased life span. Will it be worth it? This isn't to say being a drunkard is good, or that widespread alcohol consumption can't be a problem (see Russia's and native Americans' history).