Those you trust the most. Any anons remember the story of Genene Jones, the nurse who killed small children with various injections?. One possible motive for her crimes was to justify the creation of a pediatric unit at a hospital. I don't know if that is true, but I think much of our medical system is built by people willing to create or exploit health issues for power and control.

Example: Mary Lasker, eugenicist and philanthropist who managed to guide massive increases in funding for what became our National Institutes of Health, but was also prominent in the eugenics movement and was associated with what became Planned Parenthood.