So, one important criticism of Theranos, which was made at various points starting very early on, was this:
"If a substance is present in the patient's bloodstream, you still won't be able to detect it unless it is also present in the blood sample."
Theranos was always offering a product that was not even theoretically possible. Blood samples must be large enough to contain at least one molecule of whatever you're trying to test for, if it's present. When that's what you start out with, how are you supposed to "take criticism as a way to improve"?
But secretly sleeping with and living with one of her male investors likely was a factor in this debacle dragging on as long as it did and that's not typically an option for most slick conMEN even if they were willing to pursue it because most wealthy, powerful people are heterosexual males.
I have always believed her gender was a factor in this nonsense. (I am a woman and my experiences as a woman having trouble getting taken seriously is part of why I always thought this was crazy stuff and life made sense again once it turned out to be fraud.)
That resonates quite strongly with my experience, especially at competitive workplaces (big tech companies in SV). I'm a white straight man, if that matters, though.