This seems to be a great outcome if you're the drugmaker. You don't want your medicine to cure the patient, otherwise they'll stop buying it. I bet if they found an alternate drug that worked permanently after N doses, they'd bury it and never productize it.
As far as I know the pharmaceutical companies have not adopted a strategy of attempting to undermine or block surgical treatments, which you'd expect if their operating strategy was as you say.
Love a good conspiracy & not a biologist / chemist, but I don't thing such a drug is even possible in our current state of technology.
Treatments that are "one (or N) & done" tend to be surgical procedures which physical change your body or vaccines which train your immune system (which has a sort of viral memory bank).
Most other regular drug treatments are introducing chemicals into the body which your body consumes/breaks down/etc. The body is always self repairing, replacing cells, etc.
As a layperson, I conceptualize altering brain chemistry via a drug is a temporary thing the way adjusting your pools chemistry is. You have to constantly replenish with new chemicals as everything is constantly breaking down and changing.
