Why won't Hillary admit defeat and bow out gracefully?

Obama has already exceded the delegates to nab the Democratic nomination. And yet Hillary STILL refuses to concede? What is her problem? It's women like her that give the rest of us a bad name...power hungry, b*tchy, refuses to quit (that can be good in some instances but when the odds are obviously stacked against you just learn when to call it quits already!!), has to always be in the "right" and get the last word in. Does anybody else agree with me that she just needs to back out? And I hope to God Obama doesn't choose her as his running mate!