My brother is like this. Constant negativity, about everything, from work to relationships to money, to even completely inconsequential things like the new adaptation of his favorite manga or something. Everything is bad or will be bad to him, and when things actually do go badly, he has violent outbursts and punches walls, kicks furniture, and screams.

When things go well he brushes it off like it's a fluke and is never grateful about it. He constantly talks about how he was cursed at some point and I think he truly believes it, so it's a cycle of:

bad things will happen bc I'm cursed bad thing does happen, I knew it would I'm cursed and you can't lift a curse so why bother seeking help or thinking positively

I'm not sure what kind of mental illness that is on top of his crippling anxiety/anger problems, delusion maybe?

I'm not a perfect person, I suffer from bipolar 2 and I have bad days where I just sit and cry without getting out of bed, plus compulsive behaviors that affect my life, but I would never take it out on my loved ones like he does. I cut him out of my life a few months ago and while I want to eventually patch things up with him, all I can remember is all the times he screamed in my face or that time he punched his hand through a window and had to get stitches. It's not only emotionally draining but physically exhausting. You start to think like they do, it gets in your head.