Over the years, I developed a theory about why writers are such procrastinators: We were too good in English class. This sounds crazy, but hear me out.
It's sadly applicable to me down to the part where she starts talking about the current educational system: Why Writers Are the Worst Procrastinators
However, she doesn't mention something else that is a very significant part of the problem for me: plain old laziness.
Someone in the comments claims that writers are especially prone to ADHD, which is interesting, as I think I might come close to being classifiable that way.