Thats only if you consider the drug itself without all the cost of running operations and research. The actual profit margin at the company level is far from 80 percent. I suggest you read annual reports to educate yourself.
I think you're mischaracterizing the costs a little. It's certainly true that Company level profit margin is not in the 80s, but operating income is certainly fairly high. The profits come from compensating the Company for the risk that they have taken, and not necessarily straight for costs. There's certainly room to argue that the pharmas are capturing a too-large slice of the pie, and I personally welcome the debate.