Earlier quoted context omitted.
I find it hard to believe that there's some sort of conspiracy to keep police, lawyers, and prisons funded via laws against selling drugs. Have you considered that these laws are still in place simply because it's the status quo? Politicians voting on laws and drafting new ones must ultimately answer to their constituents. While the vast majority of things fly under the radar, "pro-drug" support is enough of a charge…
It's not a smoky room conspiracy. A quick google search turned up many articles about private prison companies funding lobbying[1], and I expect you will find similar results if you search for police union donations. [1] https://www.washingtonpost.com/posteverything/wp/2015/04/28/...
It's a marble halls & suits non-conspiracy lobbying thing.