When Banting and colleagues discovered insulin and saved countless lives they refused to profit from it. Their successors are making millions from Americans. The price used to be low, and it's still low elsewhere, but pharmaceutical companies have jacked up prices by an incredible amount in recent years, as has happened with a lot of other things lately. For patients it's literally a case of your money or your life.
For a very brief history of how insulin was discovered (and a sea shanty about it), see this earlier post. It was mainly the work of four people, two of whom were awarded the Nobel Prize and who then shared the award with the other two.