Hammond explains in the first novel that if you make a miracle medication with a pharmaceutical company, you would imagine that you could charge whatever you wish for it. But sick people wouldn't pay a thousand dollars for needed medication---actually, they would be furious. Insurance would not pay it. This would force you to sell at a lower cost.
But nobody needs entertainment. Nobody would stop Hammond for charging five thousand a day to visit the park, in fact the cost increase the park's appeal.