The hardest thing about writing a book of poetry is forgiving yourself for not being a better poet.
There is a finality to putting something in print, a finality that is not there when you post something to your blog. You can always edit your blog. You can always improve what you have posted.
You cannot edit a book that has been sold and shipped. You cannot improve it.
Publishing a book is way too much like telling the truth. It is almost impossible to take back the truth. We humans might be crazy, but at least most of us are not crazy enough we would want tell the truth! At least you can say that much for us.
I’d have to be crazy to want to sell a book.