Every disease is a different beast, and biology is very hard to tame. We've thrown probably trillions of dollars at cancer over the past few decades, and only in the past few years, with immuno-oncology, has there been any real hope of progress toward broad cures (there was a heady moment after Gleevec, too, but that turned out to be the exception rather than the rule).

There was just a huge wave of Alzheimer's treatments that people were so hopeful might make any dent in the disease. They all failed, apparently because the breakthrough we thought we had made in understanding the disease turned out to be specious. Had the drugs made ANY improvement they'd be on the market and we'd all be bitching about how pharma "likes to make bandaids rather than cures," and that would have been a disservice to the years of toil people put into these drugs.

Not every pharma actor is a good actor. But overall the space is mostly filled with scientists and doctors trying to make people healthier, and mostly failing.