The more I thought about it, the more I had issues with two of the pieces of advice John gave (to the point where it interfered with my ability to fall asleep last night), so I posted a response, which I also post here ...
Coming late to the party (but having linked this from my own LJ, as MissMeliss said above), I just wanted to echo the points made by Justine and Nick. A good chunk of my income as a full-time freelancer (which I've been doing for ten years now) comes from editorial work that I simply would not get if I didn't live in the NYC area.
And the car thing is huge, especially in these days of $3/gallon gas. Your check into Manhattan apartment prices created a very misleading impression, since you ignored Westchester County, Nassau County, Suffolk County, southwestern Connecticut, northeastern New Jersey, and also, in terms of surface area 90% OF NEW YORK CITY. *laughs* There are four other boroughs, and they're all cheaper than Manhattan.
I live in the Bronx. If I want to go to the supermarket, the drug store, the dojo where I study karate, the bank, the newsstand, a coffee shop, or take the cat to the vet, I walk. Other things are walkable but may require a $2 bus ride back (Target, Staples, etc.). And others are only accessible via mass transit to and from, so it's $4. And I don't have to pay for gas or insure my car or maintain my car, which is a MASSIVE financial drain.
Plus, it's New York City. Yes, I could live in a cheap big house in Ohio, but then I'd have to live in Ohio. Living in New York City is part of who I am. I'd shrivel up and die living anywhere else. (Note that I'm not knocking folks who hate NYC or who like living in Ohio. I'm just talking about my own soul here, not anyone else's.) On top of that, my entire family's here.
Also, as someone above said (I can't find the post now), it is literally impossible to work as a screenwriter if you don't live in Los Angeles.
Finally, it's all well and good to talk about shacking up with someone responsible, but the real world doesn't actually work like that. You can't control who you fall in love with, and the advice you give on the subject is a frighteningly short step to "stay with this person you married in your 20s because they provide financial security, never mind that staying together is destroying both of you mentally and psychologically."
The rest of it's good stuff, though. *laughs*