She's been told by her handlers that they are going to take Trump out of the election, one way or another. She has to be there, sitting in second place when that happens. If she drops out, it makes it harder for the Fake News to paint her as Trump replacement. Of course, none of this is going to work. But she's either too stupid to see it or likes to fuck kids and is being blackmailed. Probably both. Either way, her career is done.