Britney Spears is not sane, IMHO, and she is rich so will be surrounded by a cloud of enablers and worse. Her dad may be exploiting her financially under the conservatorship but it is possible that he actually cares for her unlike the media.
I don’t see the slightest evidence she in insane. Probably irresponsible. A bad decision here and there doesn’t make you insane.
And by the way, if she’s irresponsible, how does it make sense to put the man who raised her to be that way, in charge of her life?