My dad is a huge alcoholic but I feel no need to help them.
Why would you not want to help your dad?
I've tried to help him but he's always angry at me for trying to help him
That definitely sounds difficult, but it's good to at least try to help your family members. If you can't help him on your own it might be good to set up an intervention for him so he can get proper help.
I have an intervention at my house already and I'm going to convince to help him.
That's a good start to try to get your father some help. It's good he has you there for him in your providing means to give him support. Hopefully all this works out for you and him and he gets back on track to a healthy lifestyle.