The chunk of cash is the only reason the company is doing the research to begin with.
If finding a cure was easy then it would have been found a thousand years ago -- as some of them were. The ones remaining are hard and require a lot of resources to solve. If you want someone to put that kind of money in against a high probability of failure, they have to be able to expect an even larger amount of money to come back to them if they succeed or they won't do it.
The alternative is government funding, but then you're spending pretty much the same money. The taxpayer now has to pay the tab for all the high risk/reward research that didn't pan out. And then you're subject to all the usual government issues with bureaucracy and cronyism and principal-agent problems because you've put a thick layer of abstraction between the researchers and the patient outcomes.