People are not diagnosed unless they engage in a therapeutic relationship with a trained professional, their public status has no bearing on it. I gave the example of Goldwater because it is well known and it is germane to the current top of US government and the apparent reluctance of pundits to calling out the textbook example of mental disorder disguised as policy. As for people in your live I'd say limit yourself in recognising traits rather then conditions. Someone might appear to lack empathy in situations you find yourself interacting with them but unless you have a clear picture of their internal view and all the motivations that drive their behaviour linking it to a diagnosis might be myopic. If everyone would start out out of the norm or jerk behaviour as disorders the labels would start lose their meaning. In the same vain it is to say everyone is a bit autistic or I'm so OCD because I like my room tidy. Also manic is a specific trait usually unrelated to (the lack of) empathy: a mental state brought on by bipolar disorder or abuse of stimulant drugs, etc, just for your information.