> Most of this is drug related.
Perhaps, but we need to be careful what conclusions (and reactions) we take from that.
People from all walks of life make regular usage of recreational intoxicants, often perfectly legally. Huge, legitimate global industries are dedicated to it. If that association were the primary basis upon which to categorise as a gang, or as morally corrupt, then the Champagne region of France, and the Coca-Cola Corp (associate and maker of many an alcoholic beverage, among their giant stable of products), would be among the world's biggest "gangs". And yes, in some ways they are! but that's another matter.
So, despite the common 'drug' associations of gangs, the unique commonalities which define criminal gangs lie elsewhere, and thus a primary focus upon intoxicants, when attempting to address gang criminality - such as the longterm ineffective War-on-Drugs rhetoric - is doomed to failure, as the proof of reality shows.
Magically take away all drugs and alcohol overnight, and we'd still have a disenfranchised minority social underbelly, realising their discontent in all-new and equally potentially harmful ways.