Characters making stupid decisions

I recently finished a book that was very well written and could have rated 4 or 5 stars if not for the fact that the story hinged on the stupid decisions made by the main character. The character made one major bad decision early on in the book, and I kept waiting for her to fix it, but whenever an opportunity came up, she decided not to and just made things worse. In the end, her decisions damaged her life and the lives of those who love her. What was the point? Why did the author write a ch...