>Refusing to improve early, probabilistic diagnosis because today’s treatments are modest confuses sequence with outcome.

While you're right from the perspective of humanity taking the steps of gathering data then tackling the disease, most developed countries have single payer healthcare systems that require some level of cost-benefit analysis to approve covering new diagnostic systems.

Alzheimer's disease progression doesn't seem to have any notable preventative indications other than 'eat well, exercise and stay mentally active', all of which are standard recommendations.

Recall that this isn't an issue deciding between funding and non-funding. It's an issue deciding between funding Alzheimer's diagnostics, new GMP agonists, new screening options for highly preventable cancers, etc. Building out a dataset is nice but unless that's surplus money redirected from other programs it's going to come at a real flesh and blood cost.