the tricky part of freelance is not cash, but cashflow. over the course of a year you may make $X, but you will probably not make 1/12th of X every month. you may make 50% of your annual income in one month, and the rest on 2 other months, and not make a dime the other 9 months. being able to accommodate that and prepare for it is a key element of freelancing. i can tell you from experience it makes for many restless nights: will that client pay? will i be able to eat next week? etc.. a smart person in that situation spreads work out thru a few clients so someone always have an invoice due.
having said that, over time you will (should) build up a cushion of income to float you through the dry spells. i have found working for myself to be feast or famine: too much work or not enough. rarely is it "just right."
if you are self motivated to work, have a good network of people who have given you work and will tell their business associates, are able to do projects that keep you interested as well as projects that are more "bread and butter," are able to manage not only the actual work, but income, taxes, expenses, property insurance, health insurance (a BIG one!), self-branding/awareness, etc.. its worth a try. i have run my own show in one form or another for a few years, its been great but has had ups and downs. one thing that keeps me doing it is the schedule allows me to teach pretty much whenever i want. i work in print and some motion stuff, not web, but the work principles are the same. i DO need to reorganize myself in terms of paperwork, invoicing and taxes; right now its just some indesign documents and a bunch of Excel spreadsheets. i need to buckle down and look at some real software to do it all at some point.
for the record, i make much more than a "livable" income from freelance - IF i did not have to pay back student loans, which take a very large chunk of my income as i am trying to get risd of them ASAP.
and i know this is kind of silly but i don't really like the term freelance, to me it implies someone doing work on the side of something else. i think the term you are looking for is "self-employed" or possibly an "independent consultant."
when people ask me what i do for a living i say i "own my own design studio."
something else, everytime i start sweating i always remind myself that i can always just get a job. so why not try it?