all of those things you mentioned have damages sustained on third parties that did not have consent. And tbh, my opinion is that the banning of drugs have done more harm than not banning it (but instead, allow it to be sold safely and cheaply).

Gambling to me, is like that. Banning it doesn't stop it, and it has barely any harm other than to the person who over-indulge. Regulating it is a good idea - where regulating means there's oversight on cheating, on the platform's governance etc.