> For example, a democracy can only function if citizens are able to process complex information to base their voting decisions on.
It has worked pretty well for the last 2,500 years with voters possessing extremely questionable education. The main issue is whether a democracy has a culture of being graceful in both political victory and defeat.
> Education is correlated with health and longevity.
Correlation is not causation. Wealthy people tend to be healthy, long-lived and well educated. It might not be the education as much as having enough wealth for leisure and health.