IANAL, but contesting a will is not a simple, straightforward matter, nor is it easy to contest a will successfully.
I am the oldest of four sons. My family remains close and I expect to receive an inheritance from my mother some day. But if it turns out that she chose to leave most of her money to my youngest brother and the rest to a charity, I don’t necessarily have any grounds for contesting her will.
My Mom has no obligation to leave me ANYTHING, after all. If she likes one of my siblings better, or figures one of my siblings needs her help more, she has every right to leave her estate to him. Or, if she thinks her favorite charity can put her money to better use than I can, she has a right to stiff me!
I would only be able to contest the will if I had evidence that my Mom was senile, insane, or acting under duress.
Joan Crawford MAY have been a horrible person… but there’s no evidence she was drunk or insane when she wrote her will. She MAY have cut off Christina out of spite, but spite is not evidence of mental incompetence.