There is no "spell" or "power over men" here.
She was a conwoman. The main part of a con, is CONFIDENCE. A good con utilizes many people in the confidence game. People who rely on the trust of those in their circle rather than doing their own homework.
The people she bilked were mostly politicians and high level government personnel, and wealthy investor types with no medical training and scant knowledge of the healthcare industry, let alone actual science.
The people and businesses who avoided investing in Theranos were actual scientists and science investors who had doubts about the "technology."
So various rich old men, many of whom can barely use a smart phone, took her bullshit at face value and then sold the idea to each other, which built up more and more social confidence.
Bernie Madoff did the same thing. The people who avoided him were actual economists who knew how to do math. His marks trusted each other for advice rather than do any research on their own.
Think of someone in your social or family circle who everyone turns to for advice. Whether that person knows what the fuck they're talking about or not, they relish the role, and most of us would rather just ask that person what to do instead of doing our own research. Those types of "influencers" are useful to con men, because once the influencers realize the con, they are not likely to admit it, because then they'd be responsible for giving others bad advice and would look foolish at best. The influencers then have motive to keep the con going, whether it's conscious or subconscious.
Bernie Madoff would never be accused of casting some sexy spell over his marks, many of whom were "rich, poweful men" because he's not a young blue eyed blonde female.
Holmes didn't cast some magic pussy spell, fools.
The "spell" is the human ego and the fear of status loss, coupled with mass confidence.
The story of how George Schultz handled hearing the truth from his grandson is a beautiful example: he didn't want to look foolish and other people, like Henry Kissinger, believed it so it must be true.