Here's the real reason Clinton won't give up: she's a baby boomer woman. We Democrats may have stepped in it for good this time.
Baby boomer women are the most accomplished women of any generation in history (American or otherwise). On the other hand, they are also the generation that experienced the most sexism on the way up--there was probably more sexism before them, but bb's knew how to call it out and were more actively affected by it. This has left many women of a certain age, especially women who have reached a certain status or power, very sensitive to sexism everywhere, whether it's perceived or actual. Sadly, in most cases it's not actual, *at least not the way they think it is*. Times change, and cultural mechanisms (including power structures and their manipulations) change as well. This is hard for any person to accept as he or she ages, but it's made worse by Generation Y's seeming indifference to the whole question.
You could draw a parallel to Generation X's gunshy attitude toward marriage. That generation was the generation sent to charge over the minefields of widespread divorce, and the awkwardness, ugliness, and pain of "working out" how divorce was supposed to go have left many of us a lot less enthusiastic about the marriage institution. (Again, Generation Y treats all of this as normal: their parents had practice and reference points.)
So I think that a huge issue with the election is that women like Clinton feel they've been robbed...that the patriarchal conspiracy has been at it again. There is no patriarchal conspiracy anymore. (Admittedly, that's because baby boomer women dealt it a mortal injury.) And in twenty years of work experience the only overt sexism I've ever encountered has been from baby boomer women. It's not sexual or quid pro quo, just cartoonishly crude preferential treatment based on gender (unless the older woman feels sexually threatened by a young woman, in which case the young woman learns just how bad work can get).
But we can't talk about any of this as a society, can we? It makes race look as controversial as weather. (No one gave a Woman speech like Obama's Race speech. Think about that if you will. A politician telling women to look past a long record of injustice and keep going, since the good of the country demands it. You think race is really the shocking issue in America until you envision that scenario.) So I think we as a society may have uncovered a huge fault line that no one suspected, and it may have some serious effects on what happens in November. Are they mad enough to elect a Republican instead of letting Clinton go?
Maybe. There are a lot of them and it's a hot button issue for them, the kind that is encountered early on and can shape a life. I love my girlfriend to death. We've been together four years and I'm Committed. But after my childhood, we're not getting married.