Are any of them stupid enough to think they can beat Trump? Especially her?

Yes, and yes.

Gotta be more to it than her thinking she can win

Keep in mind, many people run for office so they can get wealthy. They get to keep any funds raised for election that were not spent.

Of course, they do have to funnel it through a "charitable organization" (that they run and earn an income from), but they profit from it.

They also can demand easy, high-paying gigs as a director of a corporation -- good pay for doing not much (since they do not have any real expertise, and their "name" is what is being bought). See: Paul Ryan.

In her case, I think she is pushed by people who hate America (and, therefore, hate Trump), and she is dumb enough to believe the great things they say about her. They don't really GAF about her, but if she can make some waves, then she is just as good a puppet as the next puppet.

From her standpoint, she is dumb enough to not understand she is a useful idiot.