It's not about the odds when all cards are known. It is about the perceived odds knowing only what you are "supposed to know".
She was "supposed to know" only that she had nothing but a high Jack with a offsuit 4. Her best hand on the last card was a pair of jacks or a pair of fours.
She was not supposed to know that he had a possibility of a flush, straight flush, or whether he already had a pair, or even a jack or higher in his hand already which would beat her hand.
So she bet 100K before the last card was seen on the chance that he had 2 offsuit cards lower than tens, or the chance that she would see a jack or a four on the last card giving her a pair.
The 47% odds would only come into play if she already knew he had a seven and eight. Then she would know it is almost a 50/50 bet. Without knowing what he had she should have thought that her chance of winning with jack high were poor.
The cheating accusation stems primarily from whether she had some foreknowledge of his hand. Her last bet was not a bluff...it was a huge risk.
I suppose if money is no object you can take those risks. Or if she was confused and made an incorrect analysis of the situation thinking her odds were better (this is where my bet would be).
In any case, I agree with others that she should not have given any money back.