I'm always a little fascinated by people like that who seem to never mature and develop, at least in terms of maintaining their relationships. This is such a basic human thing, and surely it must pain him that he's always in conflict with everyone and not welcome at gatherings. He likely blames everyone but himself for this, but isn't that just another symptom of the greater problem at work? A lot of narcissism in being unable to see others' pov, along with existing in a fantasy world where they're perfect & everyone else is the arsehole.
But something must have derailed him very early on? Do you know of anything in his history that screwed his chances of stability? Abuse and/or mental illness?
 I'm not sure exactly what it was I met him when I was 13. I never liked him at first cause he was riding a projector trolly through the lanes in English class, then my best friend connected us and we had good times.
If anything I might blame his Mother. Regardless if he was right or wrong she would defend him against anyone. That's willing to be in the wrong for argument sake. 
The middle Brother was molested and is now gay. He's successful.
The youngest Brother is a "G" and is also successful.
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In my case. My older Brother. We don't talk. He destroyed our family. 
I once wrote a piece about myself growing up, I wish I can find that thread it's was pretty comedic, yet serious and I highlighted a part of my childhood where I might have created my Brother's hatred toward me when I was 2 years old. 
Some guy wrote a vlog about SC and he showed a part of that thread, and I had to laugh cause I was TWO ! But basically I was strapped to those baby rocker chairs and we had these toys. I wanted the laser gun, and I got it, then I wanted the firetruck in my Brothers hand, and I got it, but in exchange I'd lose the laser gun. I remember it, we actually have pictures of it, and I think it programmed my older Brother to resent me for life. It might not be that, but whatever has my older Brother the way he is toward me, was certainly embedded from him since young. Could simply be that he never handled jealousy too well.