I read this whole thread. One of the assumptions of many is that one is going to walk into this profession, and with a certain amount of money, make a certain amount of money.
I think this reasoning is one of the major reasons why most traders (who approach professional trading) fail.
First, yes, its unlikely to make a consistent living off of a low capital base. But when you start trading, I belive its more important to keep your costs low and build your account.
If you start with $10k, build it to $100K, while you still work your other job. Guess what that does? First, you pay your bills every month. In my years trading early on, I had many jobs that I worked after market hours paying$22.00 to $35.00 per hour. Yes, I made money hourly. Netting 35 to 50K a year. The second and most important thing BUILDING your account does, is it tells you, with verified certaintly, that you are a good, profitable trader. Two of the things I did was: tutor high school kids in all subjects, and I started a computer and network installation business where I charged $35.00 per hour to setup and maintain computer systems in homes.
Actually it does more things. It puts you in the game with a much lower risk. It forces you to focus on method over worrying about paying your bills with your trading money (small at first even when successful).
I think the traders that read here and think if they only plop down a large enough capital stake they will make it, are running the wrong direction right out of the gate. That is a proposition that, in my opinion, leads to failure. Its OK to have multiple income streams, and build your trading skill and account equity. Your account equity and its return will tell you when you can become a professional who only trades.
The "how much money you need to make a living trading" only becomes a relevant question after you demonstrate that you are a profitable trader. If you are, then its also easy to go get more money, go to a firm that will provide the best leverage, etc, etc. etc. Or, if you are the truly independent trader, you can build your account up to a size that generates the income you are comfy living within.
You have to be good (profitable) first. Until you know you are, then you need another source of income. You know you are good when your account grows. Until then, it makes no difference how much money you have to trade. It makes the best risk/reward sense to start trading a method that works and with as little capital as possible. Obviously that means shopping for the best fees and being a smart business person too. But thats what all smart business people do.