Do you think confidence is a huge factor in success?

I almost gave up on my book project because I was concerned the quality of my writing might not be advanced enough to make high sales but after reviewing my writing today I realized it was very good. I have around 300 pages or so that I'm trying to cut down to 90 pages of jot notes and then turning those 90 pages of jot notes into a 180 - 330 page book. I also plan on self publishing and getting my millionaire cousins to loan me money for a lawyer. I could pay them back at 30% interest.

Do you think confidence is a huge factor in success?
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