Flash in the pan revenues. No company wants to have this press:

Gilead Sciences Inc. will continue to feel the financial sting this year of declining revenues from its hepatitis C business, forecasting combined 2018 sales of the drugs reaching only a fifth of what the biotech recorded at the height of its commercial success three years ago.

https://www.biopharmadive.com/news/gilead-hepatitis-c-revenu...

Contrast a statin for Pfizer: $125 billion in sales over 14 years. Lipitor alone "provided up to a quarter of Pfizer Inc.'s annual revenue for years."

https://en.wikipedia.org/wiki/Atorvastatin#History

Yeah, a company would certainly turn down a $10B a year drug because revenues declined after a few years!

Sure it’s not as successful as Lipitor (pretty much the most successful drug ever), but it’s total sales DWARF 95% of the drugs out there.

For good reason. Curing Hep C was a breakthrough medical innovation, which ultimately will save the healthcare system tens of billions of dollars (preventing end stage liver disease, liver transplants, etc)