Sure it is. Gilead made 100 billion dollars curring Hep-C with seed research investments that were probably much less than 1 billion.

So as long as this strong differential and potential for profit exists, drug companies feel competitive pressure to produce better treatments, irrespective of the fact that "milking" the pathology would yield them trillions collectively. It's effectively a "tragedy of the commons" of sorts: a single company trying to capture more of the market ruins profits for everybody else by finding a cure; behold, the magic of the free market.

They can only escape it by entering non-compete agreements and collectively agreeing not to inovate, a substantial claim that requires substantial evidence.