Pretty dumb plan by the cartels, since so many of their "addicted" customers are either dead or didn't know they consumed fentanyl and won't be asking for it in their next drug purchase. If they're cocaine users, they'll want coke (and according to the theory you're stating, they will get fentanyl with their coke, unknown to them).
At what point do these new opiate addicts realize they want fentanyl (cheaper than coke) instead of cocaine? Do they then make separate orders for fentanyl?
One major source of fentanyl in the US is and has been criminal pharmacy owners:
The founder and majority owner of Insys Therapeutics Inc., was arrested today and charged with leading a nationwide conspiracy to profit by using bribes and fraud to cause the illegal distribution of a Fentanyl spray intended for cancer patients experiencing breakthrough pain.
www.justice.gov
That's just one bust.
Of course most of the pills are coming up from Mexico, but it's my understanding that the cartels specialize in making pills that look like popular medicines like adderal and xanax (both of them sold without prescription by street drug dealers) and these are actually made using fentanyl.
So, the common vector for a fentanyl overdose (given the huge volume of fake Rx pills seized by the DEA and other agencies) is buying fake xanax or fake adderal. Is it possible that the three men in Kansas City thought they were taking something else? Xanax, perhaps, after a long day partying?
Six out of 10 of these fake Rx pills contain a lethal dose of fentanyl according to the DEA. I don't see how killing the end consumer results in more addicts for fentanyl.
I suppose the local dealers must know what they're really selling, if in fact heroin users are switching to fentanyl (disguised as something else when sold). Maybe that's the potential market. Drug dealers aren't known for their honesty and scruples, so I guess some of them off-load their surplus fake pills to unsuspecting people who think they are getting xanax or adderal.
i started this post thinking about cocaine laced with fentanyl. It exists:
It just doesn't make sense to me. Maybe I need to learn to think like a drug addict or a drug dealer. Do people actually know that they've been given coke and fentanyl in one powder? (Like a speedball?) Do they then request that from their dealers? In which case, your cartel theory makes sense - people want both products in one product and must surely be addicted to both?
There must be so many new users over time that the death of a significant fraction doesn't cause a drop in demand. Totally bizarre to think about. So scary.