I think you are giving her too much credit. She claimed she knew nothing about Princess Diana or the national anthem (God Save the Queen) and to top it off didn't know how to drive a manual transmission. Basic stuffYou do realize that when she married him he was already only sixth in line for the throne, behind Charles, William, George, Charlotte and Louis. (He's fifth now, because of Queen Elizabeth's death and King Charles' accession.) She knew long before she married him that he was never going to be King.
She is an absolute grifter who I wouldn't trust as far as I could throw her. Harry was blinded by her appearance.