I think I don't care about my parent's wedding.
Why don't you care about their weddings?
They don't really care about me so why should I care about them?
They may actually care about you more than you think. You should be there for your family so that in the future they will be there for you when you need it.
I'm 100% sure that they don't care and they are not going to help when I need them.
I'm just saying that it's important to support your family when you can. I'm sure your parents would love you at their wedding.