That's a bogus argument because it applies to non-public figures. Of course you wouldn't diagnose someone's Uncle, based on what they tell you about him, but there is plenty of information available to give an accurate assessment of someone in the public eye as much as a president.
Actually there isn't. Without a medical history, interview, and some psychological testing, you can certainly say your OPINION but not really give an actual mental health diagnosis.
You just can't and no Dr. with a real degree-not your OP-would do that.
You just jumped all over this because you don't like Obama.
He could be a narcissist for all I know. I'm just saying to diagnosis him like this is not accurate at all. It's a guess.