can't really grow up and do drugs responsibly

This is a very naive, almost willfully ignorant, understanding of how addiction and drug abuse works.

It's more like a genetic lottery. If you didn't get the right set, there is no such thing as responsible use, only abstinence or destruction.

The challenge for society is how to grapple with this genetic inequity.

Zero tolerance would probably be best for everyone, at the expense of the entertainment of some. It would also be impossible to legally enforce and seems to result in abusive policing and organized crime.

Laissez-faire would fix the above problems, at the expense of those genetically predisposed to addiction, which is a significant percentage of society, and which has been shown to have horrible social side effects in terms of crime, mental health, child abuse, and mortality.

It's a hard problem.