If the drug is needed by 1 million people, selling it for $1 will net you $1 million (let's assume all the 1 million can afford $1). If they instead sell it for

If the drug is needed by 1 million people, selling it for $1 will net you $1 million (let's assume all the 1 million can afford $1). If they instead sell it for $1000 and only 2000 people who need it can afford it, they'll make $2 million, so it's much more economically efficient.