Drug epidemics follow a natural ebb and flow and tend to be generational. As younger family members take note of the effect that life ruining drugs like crack have on elder members of their families, they have a much lower propensity to experiment with those drugs. As communities collectively recognize the impact of drugs like crack, social outreach and grassroots efforts to educate and improve the situation are much more effective than the fear of whatever legal repercussions might come from outside. Crack literally "ran its course" and that's why the epidemic stopped.

https://www.nytimes.com/1999/09/19/us/crack-s-legacy-a-speci...