In warfare, timing is everything.
And that is my hypothesis.
Hitlary KNOWS that she has high negatives. She KNOWS that early polling put her behind most of the potential republican nominees. She KNOWS that her only shot was a "short" campaign; one that doesn't give time for the republicans and independent media outlets to pick her apart.
My hypothesis fits with the Klintonoid pattern of political comeback masterstrokes.
Only one problem:
She has NO MONEY.
Big disadvantage.