I'm not going to my niece's first birthday party
But it's her first! Why don't you want to go to her birthday party?
It's such a hassle so I think I will cut this one
While it's your right to not go to family celebrations, you still shouldn't sit out on very important milestones. Seeing a first birthday will never happen again. After this, you might be too lazy to go to more and miss seeing her grow up.
I don't like the idea of my money going back into my extended family. We hate each other.
It doesn't matter if you all dislike each other, your niece has nothing to do with it. I believe family should stick together for the sake of the young ones, so they will have a sense of normalcy and have a happy childhood!