In a healthy society there would be no need for intoxicants with so severe harms (BBC list for substances by harm is a good reference) and thus no exposure for a addictive substance.
Now the norm decides that, almost without exceptions, we must all be exposed.
This is true of coffee, sugar, alcohol, social gatherings, work, play, and everything else in life.
It's legal only because it's been grandfathered in, from before legal systems were created.
Yeah but we don't live in a healthy society. We have more abundance and more advanced healthcare and drugs than ever before, but we are sick in terms of missing social connections and family unit, even in big cities. Hence why mental illnesses and substance abuse are going up.
People don't thrive on GDP line go up and cheap large screen TVs. People need friends, family, and a support network.