We were spending a lot more on AIDS research 20 years ago than on Alzheimer’s today:
https://www.ncbi.nlm.nih.gov/books/NBK222902/
This produced great results for AIDS, which many people thought would never be treatable.
Anyway, medical research is expensive. Considering the number of people who will get Alzheimer’s and the cost to deal with the disease, you would have thought we’d have been spending more on research for the past several decades.
Maybe soon we will all agree that it’s probably worth investing more on research?