Kathleen Sebelius was put in a politically impossible position. There was zero possibility of the technology supporting the ACA ever working as originally specced. She should have recognized this instantly, but even if she did, what could she have done?
I'm sure she's in a financial position where she didn't have to have the income, and if she had any integrity, she would walk. Further, when questioned by the press, she wouldn't give the 'spend more time with my family' canned response, she would be truthful.
She wasn't placed in a position. She sought out the position. As do all politicians.