What someone will pay & what someone will sell @. Normal basic econ.
Edit: (I can't seem to reply) I think non-gov monopolies are ok. You'd make a ton of money in your example, & then be able to create more drugs. Generally, I think it's good for talented people to get resources. Superior resource allocation.
There's nothing talented at all about buying rights to a drug and then raising the price of it. Monopolies hurt consumers, why would you think that's okay? Especially in a field like pharmaceuticals where peoples lives are literally on the line?
This isn't normal basic econ. This is a monopoly market.
Let's say I create a cure for a truly horrible disease like Huntington's. Let's say it cost me absolutely zero dollars of R&D, I just happened upon it in some weird stroke of happenstance and the FDA does a rush approval and gives me a grant for even those costs, basically fantasyworld but $0 expenditure by me so everything I make is pure profit. And let's say I bring this drug to market and I give it a very controversial price. Which is that I will cure you of Huntington's if and only if you pay me 1 million dollars or all of your worldly possessions, whichever is higher. Do you believe I should be able to do this?