Using someone else’s quote at the beginning of each chapter makes it appear that your points require an expert’s credibility, which you don’t have.
If your book has no index, it’s obviously self-published, and not with much care.
Dozens of testimonials are, well, a dime a dozen.
You’re not a “best-selling author” because your book, sold a couple of thousand copies.
If you have to keep telling me “my book did very well” and “it’s been very well received” I’m already skeptical.
You’re not really an author until you have three commercially-published books; otherwise you’ve simply had a couple of good ideas.
We all have typos in our books, even from major publishers, but inaccuracies and “facts” that are untrue are killers.
If your points aren’t supported by social proof, then you just have theories and opinions.
If I don’t learn anything reading the book that isn’t already on the dust jacket, then you’ve brought shallowness to a new depth.
If you’re using other people’s stuff without attribution, you’re plagiarizing, and if the other person has a strong brand, you’ll be found out.