My personal theory is that the following is why so much research is ineffective: A drug development company finds 5 potential cures. They throw out 3 that are natural or unpatentable as uneconomic. They throw out a 4th because it is predicted to be modestly profitable and may only break even with regulatory costs. They pursue the 5th one and chance being what it is, it never gets to approval.”
A lot of research takes place in academia where this isn't a consideration. Furthermore, even natural substances are patentable. Maybe not the molecule itself, but the application. But yes, development costs are fiendishly high. It can take a decade or more, and hundreds of millions to billions, to get a drug to market.
And that's not a sure thing. Drug development isn't for the faint hearted.