The mystery is why she didn't run in 2012, when her "listening tour" showed she'd win in a landslide.
Resigning as governor was obvious - Rats were exploiting a loophole in the law where they were able to file constnat frivolous suits against her (which they never won) that she had to defend with her own money, and which also took away from heer ability to run the State. After her nth win, the legislature should have admitted the abuse and fixed the loophole, but no way - they were behind the harassment in the first place. Stepping down under those conditions, IMO, was brilliant, and showed she cared more about Alaska than forcing the State to deal with her personal issues. That's true leadership.
Your impression that she is a quitter also has to ignore the tremendous fight she made - and again, won, against the entrenched good old boy Republican and oil factions up there, which no one had been able to crack. On the other hand, you're paid to mimic soccer-mom feeling-words and link them to the word quitter in order to target female middle-of-the road social conservatives who read this site, so I understand that part of your post very clearly.
IMHO the "powers that be" threatened her or her family.
If elections really decided things do you think they would let us vote? Or something like that. Mark Twain.
I suspect 2012 was her chance. I personally think she was done in by Bristol getting harassed at that bar when she was filming her reality show. With Bristol and Willow against a run—and probably realizing that she couldn’t win without her family behind her, a better organization, and more money than she’d lined up at the time—she called it off.