One thing you may notice about this trope, especially when applied on a worldwide scale, is that it assumes that all countries in the world use the American healthcare model, even though countries with socialized healthcare are very much interested in cures for chronic ailments to reduce the tax burden their systems create. Within the US, it assumes the people working within Big Pharma are simply saving these cures for themselves, their families, and the ultra-wealthy, even though rich people die from cancer and other illnesses all the time.
The people who push this theory the most are either not very knowledgeable about the subject, or they're trying to sell you something themselves. Also, hiding a cure would be unwise from a business standpoint for at least four reasons:
- That would create a huge chance for someone else to create a knock-off. To patent a cure, they would have to admit they've developed it,
- Developing any drug is extremely expensive: research, development, and testing it with large numbers of animal, and later human, test subjects, so why would anyone go through all that with no chance of making back the millions they've spent?
- The benefits of fame and PR that would come from being "The company that cured cancer/AIDS/whatever!" would be immense.
- As the COVID-19 Pandemic has shown, there's no telling when a new illness can pop up and ravage society. Humanity will never be 100% disease-free.
