It seems to me that studying the condition of an individual person is qualitatively different than studying a cluster of mysterious conditions in general.
To study a particular person, you actually need one nearby and have a relationship with them that helps you studying them. This sort of relationship management is not what the stereotypical nerd wants to do.
When it comes to studying a cluster a cluster of mysterious conditions in general you come to topics like Chronic Lyme Disease. If you study it you see that there’s a community that believes that there’s such a thing and at the same time the mainstream establishment that doesn’t believe that Chronic Lyme Disease is a thing.
Social reward for solving it: Many people currently alive would be extremely grateful to have this problem solved. I believe the social reward would be much more direct and gratifying compared to most other hobby projects one could take on.
Solving a mysterious health issue that mainstream medicine doesn’t solve means advocating alternative medicine treatments. In many cases, this has more social costs than social rewards even if the treatment helps some people.
Interestingly, both France and South Korea are notable for their atomic power plants. Knowing the direction of causation is seldom easy, but maybe anti-nuclear activism turned the issue partisan?