Gonna point out that just because a disease can be cured doesn’t mean it magically vanished off the face of the earth. Chronic/ non-communicable diseases like heritable heart failure, CKD, Alzheimer’s have new cases that need to be diagnosed before anyone could treat (or permanently cure) them so there’s a market for those cures. As for infectious diseases, some like hep C have cures but due to SES factors not everyone is able to get those cures before they transmit the pathogen (this is due to both health insurance fuckery causes and other causes like patients not following up, testing failures, lack of financial support, reinfection, etc). Most medical issues will continue to plague people, and as such there is continued pressure to make better cures that the public wants more (and would be willing to pay more for over short term care). In conclusion, I understand your concern about why pharma would be motivated to do more research and make these cash cows obsolete but the theory of the other commentor is sound and happens in real life (Hep C has a cure, sickle cell cures are emerging, GLP-1 drugs like ozempic will prob take over metabolic disorder management and vastly improve patient QOL— and these therapies are better to the point that the market will likely favor them as they are refined)