My parents don't help themselves so I'm surely not going to help them. Plus, they think I'm stupid.
Can you tell me more about how they think you're stupid?
Well, they have been asking me to do endless things for them.
They're your parents and I do not think they think you're stupid. The best way to resolve your relationship with them is to communicate to them that there's a limit on things they want you to do and try to make them understand that.
I don't have time for that. I have better things to do.
If you want the problem to be resolved then you need to make time for a conversation with your parents. I genuinely do not believe they think you are stupid and talking to them with help you realize this and feel better about your relationship with them.