why does he act like he hates me when he's drunk?

I'm not a psychologist but I'm a drunk. 💀 Being drunk makes it easier to say things you wanted to say anyway, also makes you confused about whether someone actually did something wrong or you're just latching onto something because you want a reason to lash out. Either way, leave him, kill him perhaps. I've seen several of your posts on the topic and let this relationship go.

There's 3 types of drunks:
I think we know which one your boyfriend is.
If you weren't there he'd get mad at someone or something else when he's drunk. It's just that you happen to be the softest target for him to pick on when he's drunk.
It's fair to say that the drunk him is a total idiot and somewhat evil. Just as well the sober him makes up for it.
Jekyll and Hyde in real life.

He can’t hide it, he hates you badly.

well, that's not beyond the realm of possibility, but why wouldn't he just leave me then?

He needs ass.

sounds like you need to get some tbh

not every single time but pretty often, my boyfriend gets so mad at me for literally no reason, picking on the tiniest things just because something else ****ed him off, like trump and the stock market today. but the next day, he makes up for me for it by a hundredfold and treats me better than anyone ever would. like what's the psychology behind this

Yeah, I'd agree with Dunnig that it doesn't have anything to do with you. He's just trying to expel his anger somewhere and you happen to be there. Last time I slammed my fingers in a door, I shoved my friend for absolutely no reason except I was in pain and unable to think straight. But if his anger issues are more serious than just nitpicking, maybe interest him in some meditation or therapy. Or just talk to him. Like, 'hey, I notice when you're angry it seems like you take it out on me sometimes. Like, I get it, but could you try to improve on that?' If he realises he's doing it and thinks about what he's saying, I think he might be able to stop himself.