"Markets" are poorly designed for health care/research investment in general. Just like roads, education, general science research, etc... It just doesn't play well with being largely run with a profit motive.

That's not to say there's on place for the private sector there, but there is massive friction between a profit motive in drug research and you know, building a more healthy society. See the "new Adderalls" like Vyvanse that offer no benefits over Adderall, but Adderall's patent is up so it can be made by generics and isn't as profitable anymore.