Do you think writing a book is really difficult?

I do a lot of self editing where I will come up with an idea and then abandon it because it does not measure up to my standards. I think most people would be satisfied but I'm not, I always think it's doesn't measure up. I think I'm more talented then many writers that are well known in the industry but I always feel like it's not good enough. I have loyal friends but I don't know too many that would be willing to spend 70 hours reading my content and editing it. My biggest challenge is not having mentors who can help me improve my skills. I'm not in an official writer's school where I can access knowledge on how to improve my writing skills.

Do you think writing a book is really difficult?
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