Taking the cost per drug brought to market for la roche $7,800,000,000, then the cost per treatment of drug being $75,000, this equates to treating 100,000 to recoup the initial outlay of research.
When you factor in the other costs such as synthesising the drug (6 step synthesis, isolation of 5 intermediates) and hospital staff wages, the actual money generated per treatment is going to be far less than 75k so you are probably sliding towards 200,000 treatments to break even.
Add the fact that inflation is escalating and people require new drugs, la roche are going to have to turn a pretty profit to continue funding further research. These are pretty simple assumptions and calculations but people at la roche will have analysed to death how much they must charge to ensure the company continues to the future.
Unfortunately drug companies are pulling out of research into drugs such as these where only a very small % of the population are sufferers. It is much better (in their eyes) to find treatments for conditions a large % of the population suffer from which they can easily recoup their financial investments.