Yeah, I people who want to do drugs are going to do them regardless of if you make them legal or not. I don't see why it should be a crime to put chemicals in yourself of your own free will.
Discussion
Drug use is not a crime. Locking people up for drug use is a crime.
The typical argument is that addicts commit crimes, but if you steal something or hurt somebody, those things are already crimes and you should pay for them.
To criminalize the potential to cause harm is the same logic that the gun ban lobby is operating on.