FWIW, the average cost to develop a new drug actually is well over a billion dollars, meaning that a lot more units would have to be sold and/or the price set a lot higher for the effort to be worth it. The interest alone on this sort of expense would be well into the hundreds of millions of $ and growing at $140M annually before the first dose is sold. If the company sells 1M units annually they'd need to charge $150 just to cover the interest and around $500 per unit to reduce the deficit in a reasonable period. Any less and they would have been better off to put their billion dollars in the bank and develop nothing.
I agree with you that it is easy to look at that $500 price and scream about the apparent 4900% profit, but that's what is needed to make it worthwhile.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
