I have a few thoughts on these issues. - Hygiene hypothesis: Cleaner environments and changes in social patterns (for example, less undirected outdoor play, f

I have a few thoughts on these issues. - Hygiene hypothesis: Cleaner environments and changes in social patterns (for example, less undirected outdoor play, fewer siblings) are leading to being exposed to less germs as kids, which causes the immune system to become oversensitive and trigger itself. - Diet / exercise: Particularly for diabetes and obesity. The cheapest, most convenient food is unhealthy due to subsidies and a less local supply chain (100 years ago local stores probably stocked a lot of local produce and little packaged / heavily processed food, not so today). Restaurants increase portion size (I suspect this may have something to do with labor costs increasing due to Baumol cost disease and other factors). Fewer people have jobs with lots of physical activity. Erosion of traditional gender roles and modern economic pressures mean fewer couples/families have someone who stays at home and cooks a labor-intensive dinner every day. - Low-hanging fruit: Diseases that are easy to vaccinate or otherwise cure have already been mostly eliminated from advanced nations (and in some cases, worldwide). Diseases that are hard to cure have been turned from death sentences into chronic conditions. (If you had diabetes before the medical community knew much about blood sugar or insulin, you'd probably die pretty quickly.) - Perverse incentive structure: As other posters have noted, it's a lot more profitable to develop a drug that alleviates symptoms. Possible solutions: Cash prizes for curing diseases (money comes from a non-profit-oriented party, risk taken on by private sector), government/non-profit funding of research (money and risk both borne by non-profit-oriented party), and government/insurance allowing cures to charge equivalent rates (e.g. a shot for diabetes "should" cost about $36,000, because that's the price of taking $100 of insulin every month for 30 years, but would the developer be allowed to charge that much? Money comes from patients or their insurance, risk taken on by private sector).