It may not have worked, but at least it was something.No, it wasn't. It was worse than nothing.
* They spread misinformation so blatant that people had no way to judge the actual dangers. Marijuana is federally illegal to this day, and despite literally millions of people using it safely, we're still telling kids that it has no valid use. That made it impossible to get out coherent messages about the more dangerous drugs.
* The War on Drugs was also a War on Drug Users. Money was spent trying to prosecute, when it could have been used to treat addiction. And it certainly wasn't spent trying to look into the underlying causes of addiction -- despair, poverty, mental health, etc.
* It created a hostile relationship between police and citizens. Rather than being able to ask for help, citizens were terrified that they'd be arrested for using drugs. People died because they wouldn't go to hospitals, for fear of being arrested. And, like alcohol prohibition, it fostered violent gangs.
* It utterly devastated black communities, directly and indirectly. Among other things there was differential prosecution that put more black men in jail.
* Despite "doing something" they allowed Purdue Pharma to sell their opioid as safe, causing rampant abuse.
There is a very good chance that this would have turned out better if they'd done nothing at all. There were many other things that could have been done, but instead they poured many millions into making people's lives worse.