The idea that drug laws cause crime doesn't fit the evidence very well.
You have many polities with harsh drug laws and enforcement with little crime, and many polities with loose drug laws and enforcement with lots of crime.
When a drug is legalized, like say marijuana, you don't see any drop-off in crime or arrests. Many people who were getting busted on marijuana charges end up getting busted on something else (often the whole reason they were busted on a drug charge is because its easier to prove or a plea bargain, but they are violent criminals).
Young low IQ men form gangs and like to participate in violent tournaments. They need little excuse to do this, and where you legalize one drug they can choose another, or hoes, or dice, or protection rackets, or who dissed who at a party or on social media. It's enlightening to actually witness trials related to why people kill each other in the ghetto. If you removed drug illegality as an excuse, which many jurisdiction have de sure or de facto, they just use some other excuse.
The main issue with drugs is that it lower IQ and inhibition in users and especially addicts. Such people are a lot more likely to commit crimes under the influence. If you legalize drugs you will get more users and more addicts, which isn't a good for crime.
The simplest way to stop crime is to demonstrate clearly to young low IQ men that:
1) They will be caught with a high degree of certainty every time they commit a crime of any kind.
2) The punishment will be very harsh and thus not worth the risk of getting caught.
If you can demonstrate this effectively then through a mixture of deterrence and incarceration you can eliminate crime, even in terrible demographic circumstances. The question is whether the stakeholders in the state of the willpower to do this.