I'd love to read what a crime syndicate does to improve their activities. Doesn't mean I agree with them... but no doubt it's really interesting and I might learn something from it.
Drug smuggling submarines. There was the court case of El Chapo and his IT guy testified about how he requested everyone's phones to be bugged. Also a secure comm network built for his organization, that then ended up bringing him down, because the IT guy folded (the FBI made a deal with him), etc.
Also you could learn a lot about tunnel building, and tunnel detection.
The crime syndicate scenario would be actually better because unlike advertisers, they actually provide (illegal) products such as drugs that have demand. I can give you examples of people happily buying drugs, but I’m not sure I could ever find someone who’d be willing to look at ads/spam voluntarily, let alone pay to do so.
Also you could learn a lot about tunnel building, and tunnel detection.