There isn't really much wrong with a little crack or meth among friends, I know that's hard for many to understand, but its the truth.
The bigger problem is the crime associated with the production and trafficking of the stuff. Much of this is due to the fact that its criminalized in the first place. Its intentional and its a cycle that feeds itself. Those in law enforcement don't want to change anything, its job security. They can play whack-a-mole generation after generation with street level dealers. It doesn't change the amount of drugs on the street or accessibility, but it does keep people employed, it does keep people in jails/prison (many of which are for profit and privately run).
So again, a city DA going out and busting 50 street level dealers does absolutely nothing to curb drug use. It does nothing to improve public safety. It does nothing to treat drug addiction. Its a huge political boon for many involved, makes for great headlines, and creates the illusion that the DA and law enforcement are actually doing something meaningful.
The same applies to busting a steroid dealer in the gym. Utterly pointless.