And OP seems very concerned about medical insurance, which might suggest something bigger behind the curtains. Young folks often think they're invincible, and medical insurance is last in their list of worries.
(BTW I agree I'm reading a lot into his post, Sherlock Holmes style, but without confirmation one way or the other, its hard to say if I'm on target. In any event, I do not believe that the OP would share your umbrage, given his post.)
But the primary false thing I want to address is the tacit assertion that "Telling someone they have NPD traits is a personal attack." I understand that assumption because, sadly, accusation of personality disorder has become a common style of personal attack. It's very similar, actually, to the classic status of "homosexuality" - once a pejoritive, now mostly just a fact. And I'm not sure if you noticed, but HN has a LOT of psychology-related content. As a group people here seem to show a lot of admirable compassion and empathy for each other's vulnerabilities. I think it's a remarkable feature of the place, and I hope you can take my words in that context. NPD is quite common in the world, in our field, and its entirely posssible to be a good person who struggles with NPD.
Your protective instinct speaks well of you! But you may need to reassess whether or not I actually attacked the OP, given his request and the context of my response.