“I want to write a book.”
“I want to leave a mark.”
And the people who get serious about the idea write the book, and they leave a mark.
These pages are the mark. They say for now and ever, “This is who I was and what I had to say. This is what I saw and what I think it meant.”
“These were my struggles, which may resemble your struggles, and how they affected me and how I tried to overcome them, and I write them down so that you may recognize yourself and find help in overcoming yours.”
I suppose you have to have unmitigated ego to believe you have something important to say that might help make life a little easier for the people who happen to bump into your words. Or maybe you just have to care enough to try to help other people.