Isn't this evidence in the other direction: if the drug already existed and was acquired for $11 billion, then that suggests that they expect the profit to be about $11 billion. Otherwise, wouldn't they bid up the price more?

In the 18 months following Sovaldi’s approval, Medicare alone spent $8.2 billion on the drug.

I know that's revenue and not profit, but that doesn't even include private insurance, self pay, or sales outside the US.