Sure, there are all sorts of rare diseases that could be cured, but there's no money to do the research. People have fundraisers to try to make it profitable, e.g. [1]
Well that's because the diseases are rare. Regardless of profit, it makes no sense to work on a drug that will save 20 lives, when you could work on one that saves 200 lives.
Another part of the problem is that the cost of getting drugs approved is ridiculously high.
Another part of the problem is that the cost of getting drugs approved is ridiculously high.