Why do people who *know* they have an issue with you still answer your quetions?

It baffles me. They know you don't care for their advice or for their opinions and you have made that clear to them many times before, and they feel the same towards you, yet they still answer your questions. Not only do they answer your question but they find some way to subtly insult or belittle you in their answer or sometimes they flat out come in there and tell you that you are an idiot. Why can they not steer clear of your questions when they know they will only give a spiteful answer that is not going to be helpful?