But Dave, drug use is a victimless crime!

Uh, nope.  There's always a victim.  Take this story about a 19 year old Alabama girl getting arrested for having sex with a 14 year old boy.

The girl’s grandmother, Peggy Thompson, told the press (via Toronto Sun) that Mekenzie had lived through a difficult childhood, moving from “flea bag motels” to at least one mobile home with parents who abused drugs and who abandoned her to raise her younger brother on her own. Things were looking up when the kids finally went to live with their grandparents. 

Thompson said that Mekenzie got a job at a rug plant after graduating high school, but fell apart after her grandfather died. Unable to work due to an injury, Mekenzie sought companionship and fell in love with a “boy who looked a lot older than 14.” 

The police chief said it was no excuse for what she did, and that she showed no remorse for her actions.

The reason this girl has such a twisted, poor view of relationships is that during her formative years, she didn't have any examples of a good relationship.  This poor kid was set up to fail from the get-go, by parents who abused drugs.

So who's the victim here?  The girl, obviously.  Her brother as well.  The grandparents, although they might be culpable if they're the reason the parents were abusing drugs in the first place.  Sometimes it's a pattern, sometimes it's not.

Who else - the boy?  Meh.  When I was 14, if I had a chance to bang a hot 19 year old I would have jumped on it, both literally and figuratively.

How about the public who now has to support a girl in jail, a child who's mother is in jail (Lord, just how messed up is THAT kid going to be?) and the family of a 14 year old boy who are now grandparents much earlier than they wanted to be?

There are lots of victims from drug use.  You can find them littered all over America.  This is just one example.