Only in the last week an "adult" male was sentenced to gaol for a
one-punch assault after drinking at least 10 schooners of beer.
I would be lying on the floor after 10 schooners, and any attempt at a one-punch haymaker with my arthritic hands would deliver me to hospital with a mangled hand and leave the other person laughing.
To deliver a punch that kills, or in this case caused permanent disability, generally requires and involves the strength of younger men. No person over the age of 18 is likely to make "adult" or rational decisions after 10+ schooners, and trying to uncouple abuse of alcohol as part of the problem is not facing up to reality.
So there is a huge difference between the idea that "a legal adult is responsible enough to make a decision that may risk their own well-being" by say bungy jumping as against drinking to excess, losing their social inhibitions, and taking out all the frustrations in their life on an unsuspecting victim.