And stealing to support your habit is not a crime?
Theft is a crime and no reason will change that. Even if a person is stealing water to save their life, it's a crime. Considering the person stole water to stay alive, the crime they committed in doing so would be trivial compared to saving their own life. An impartial jury could decide the case.
Or how about being so stoned that your family suffers from your "detached existence" or your job loss because of your inability to be productive at work?
"Victimless?" Hardly.
You should surely go for this. If you think you've been harmed by a person because they smoked marijuana file criminal charges against the person (perhaps file an assault or harassment charge). Plead your case before an impartial jury and let them decide if you were harmed by the person.
And if you've been affected by anothers drinking or drug use there is a place for you at Al-Anon. You can find information at 1-888-4-AlAnon. I believe there is also a group called NarcAnon, but I don't currently have any info on that organization.