I'd be cautious about taking heart in the number of books she's sold.
I've no hard evidence to support this, but I'd wager that the folks reading her book are the same folks who have already identified the Carnival Barker in Chief as the corrupt, lying, worthless sack of excrement he is and that no MAGA hat wearing folks are interested in reading anything, let alone something that questions the fitness of their made-for-TV cult leader. In short, her book is being read by the already converted.
It may well be that living in the Heartland™ has caused me to become jaded about my fellow Americans, but of the legions of Trump supporters surrounding me I can confidently state that they are interested neither in acquiring the book nor learning of its contents. To them, it is a "Fake News" book written by a disgruntled family member.
It's mourning in America again.