Hmm, with me i know i'm always desperate to try and make the person who involves my ptsd understand, however several times i've had lines like "i don't think you have ptsd" "its part of growing up" etc. It drives me mad. I think it angers me so much because (in my case) the person can't ever interperet how it feels.
I think in analysis of myself i want some acceptance that i'm actually having a hard time. A problem for me is that ptsd is "invisible" - others can't see it. The idea of that infuriates me because i'm struggling yet no one can see this. So i suppose in attempted answer to your question(s) maybe its a want of validation for the way we feel.
However i also agree with previous comments of not wanting to feel alone, i think ptsd can be isolating?