They are in equilibrium for people buying the product with the kickback. Other brands now are artificially more "expensive" and have to issue kickbacks to remain attractive, or the people who aren't participating just have worse rates because they might accept kickbacks in the future even if they aren't using drugs that offer them today.

My understanding is that your policy funds are effectively "mixed" with other people covered by your insurance company.

So, I think it could very easily be a net transfer of money from people who aren't using that drug category but have insurance policies used by people who do use that drug, to the drug company at the end of the day.