Family guy

Not even just their money, but also your control over them. They are less likely to disobey or rebel against you if they are sick and believe hat you are treating them. Once they do find out the truth about having a cure, they will still be ill and too sick to rebel against you and you can just threaten to stop treatment if they tell anyone.

Even with a cure, people will still get cancer. People cured of cancer do and will get cancer again. The idea that creating a cure will undermine profits is ridiculous. Look at the recent insane price hikes for medications already on the market. The company that creates the cure will price it according to current treatment, which doesn't guarantee a cure. There's more money to be made in a cure than treatment.

A patient cured is a customer lost

that doesn't make sense though. think about it. you have thousands of companies from multiple countries working on a cure. many of which are independent or colleges. any time a new discovery is found it is printed. once it is printed every other company will use that knowledge to further their study. that is a lot of people to silence. no one is going to go from 0 to the cure for cancer. if one person is close everyone will be close. this is taking a big crap on people who dedicate their lives to curing cancer. many of those who are not doing it for the money. other things, maybe, but you still face the same problem. this is nothing but conspiracy theory. yes big business is evil, but i don't think they would ever be able to pull that reach. there are to many individual researchers and each are rushing to print the next discovery.

Ahh sweet non-american health care

Of course, because it's so easy to find a cure.

Plot twist: It's not private companies trying to milk "customers" of huge profits, but the government. When health insurance is controlled by one entity (single payers, that is, government health coverage for all) there won't be anyone to provide any alternative to "managing" illness.