Just to expand your math in a different direction, going from 342 customers to 684 adds $9576 in costs, but cuts the price by 1/2 (plus $28). $21,139.
Going from 684 customers to 1368 adds another $19152. They break even at a $10,598 price point.
From 1368 to 2736 customers adds another $38304 in costs, but reduces the break even price point to $5327.
From 2736 to 5472 customers, another $76608 in costs, and a break even price point of $2685.
They are recouping all their additional costs, and making exactly the same profit charging 5472 people $7/day instead of 342 customers $115/day.
How many of those 1.2 million HIV patients can afford $7/day? If just 1% of them are willing to pay $7 a day, they will more than double their profits.