Reason number seven to keep your day job is your writing market might dry up. Yeah, right some nay sayers may be thinking but it happens all the time. Magazines fold, website's disappear, book lines are dropped, editors are replaced and you the writer are left to start over.
Again, while you learn search for new markets, hone your writing to fit a new magazine's style or revising the manuscript that took you six months to write and target to a book line that now closed...it helps to have a day job, which of course translates to a steady pay check. Depending on what you write, it may take anywhere from six to eighteen months to get yourself re-established enough that you are getting article assignment or multiple book contracts.
What if these new markets purchase your work but pay less per word in the case of a new magazine market or the advance is lower on the new book contract. Are you prepared to produce more work to make up for the loss of income?
Although this sounds depressing, it is a reality for freelance writer and another thing to consider before giving up your day job.