"Secondary gains" is the term applied to the gains a person obtains through being ill or injured: through defining themselves by their diagnosis. These gains could be monetary, social, or personal. 

On the surface it seems illogical to think that a person could obtain any gain from any diagnosis, and no professional medical provider would automatically assume that any patient would have any gain from a diagnosis. How could someone possibly benefit from never being able to get out of pain after an auto accident, or never be able to heal completely from a surgical procedure?