she was sent in to set things in order in the Earth kingdom...she did that, but it kinda turned into "by any means neccessary" type thing...then she decided not to turn it over cause, well, why should she?? Wu clearly wasn't the right man to lead...then, cause she's already drunk with power and going more crazy by the second, decides to take back the old earth kindom properties too...

her thinking is deluded, but i get where it came from...plus, she managed to beat the Avatar in single combat and has the most pwerful weapon anyone's ever seen, or course she's feeling on top of the world...