"Why don't we teach effective exercise, sports, and fitness in schools?" We do. It's called gym.
Um no, and that's part of the problem. In my experience, gym class was a Hunger Games like spectacle for the athletically (but not otherwise) gifted to enjoy their brief decade in the sun at the expense of those who will peak much later in life (but of course, they're more likely to be sedentary in part because of such a negative early impression of physical activity). Evidence? Do I need to mention anything else beyond Shirts vs. Skins Battle Ball? What kind of %$*!ing psychotic thought this sounded like a good idea at the time?
"Why don't we align our medical system with prevention instead of expensive and risky cures?" That's a good question, actually.
No money in it for big pharma, a segment increasingly under attack from the FDA for many of its practices and for which many critical drugs are facing patent expiration. So now they're trying to play good guy by increasingly focusing on orphan diseases ($10K to $500K/year per patient) where if someone blocks a promising therapy, its entire population of victims is doomed. And since these are the long-tail, it also creates an effective barrier to entry for smaller competitors.