Like why am I always having to buy your ass a gift every year on the day you were born just to feel good?

Because you actively are doing that yourself. No one makes you.

I can choose to not go because I don't give a single micro-ounce of a fuck about your party.

Then do that. If you go, that's on you.

My goodness, I hate people like this that make me go to their birthday party.

Are you still living with your mom and rely on her for transportation or something? That's the only way I can see you being forced to go. Unless you've got a crush on the person but aren't mature enough to say you can't/won't go.

and yet you guys go out your way to go buy me shit when I didn't even ask for it. I'm forever grateful for the nice gesture, but I just don't want it nor need it.

Donate it, sell it, toss it, destroy it with fire, whatever. But also that's kinda the point of gifts. It's a physical sign of appreciation.