In the modern world, it's not ideal to create a drug to cure something. Once people are cured they no longer need your drug. That's why we have so many drugs like Lipitor and Viagra that treat symptoms but do not cure.
The "problem" with Sovaldi/Harvoni is that the patient only takes it for ~90 days, and then they're cured.
The drugs are cheaper than regular treatment of Hep C - which ends in liver transplant. Do people think the price tag was just random? No, it's because this is a price at which the taxpayer saves money by curing the disease vs. blood transfusions, liver transplants, lost economic value, etc.
Not to mention that the waitlist for a liver transplant is getting halved as we cure Hep C.
As we slam Gilead the other really evil pharma companies like Pfizer are taking notes and patting themselves on the back for creating drugs whose end goal is to addict the consumer.