I've had friends who've died from purchasing bad drugs at raves from people who were looking to make money and run. In one situation it ended up being rat poison. The guy had other drugs in his system, and combined with the poison his body went into shock. With darknet markets and independent lab testing networks, this type of thing doesn't happen.
People are still going to use drugs. I'd rather law enforcement go after the guys who are selling rat poison at raves than the guys who are setting up safe distribution networks.
It is not a reasonable argument for an individual to make to try to justify their illegal get-rich scheme.
If the law is hurting people, and breaking the law helps people, it's completely reasonable to use that argument to morally justify your illegal behavior. I'd be interested to hear your argument why it is not.
Edit: Though to be clear that wouldn't work to justify all your illegal behavior, if that included like hypothetically trying to have someone killed.