Here’s an article on freelance writer earnings:
“Earnings for all types of freelancers
12% make over $100 an hour
41% make over $70 an hour
67.5% make over $50 an hour”
via www.fabfreelancewriting.com
You need to be making money as a freelancer before you quit your day job. And you need to have a cushion of savings. Six months' of income is OK, but 12 months' income is even better.
Freelance writing is a attitude, and a mindset.
You need to be able to do the work, and be a self-starter.