People with no income trying to run a side hustle/biz usually become desperate. This energy scares people with money away.
This is a way bigger deal than most people think. It's not just that you'll scare away clients (and you will, and the clients you get will be the ones who care about having leverage on pricing, NOT the clients you want) it's that your priorities will get all messed up.
OK, you have no job so you can work on a business full-time... except if you have $0 in the bank, you still gotta pay your own nut. How long is it going to take you to become profitable enough to take a paycheck? Can you cover your old income in the first month? Probably not.
So how are you going to do that: take freelance contracts, which makes it less viable to work on the business full-time? How many freelance contracts are you going to need, how much time are you going to spend prospecting, how much time will it take you to fulfill those contracts? Where will your energies be focused: on the business, or on your freelance contracts?
So you're in the same situation as you would be if you had a job and were trying to build it on the side. You're probably going to be making less, especially if your effort is spent on client acquisition. You may not have enough time to work on the Fastlane that you wanted, just because you're trying to build a freelance stream of income.
Your priorities are now focused on getting income NOW and not on building a sustainable business.
If you have more money in the bank (let's say a year's salary), you can take more time to build the business correctly, build a team, etc, but you still have questions that must be answered. You still need to demonstrate a need for the business. You still need to demonstrate that your business model is scalable and profitable. It needs to make CENTS.
Let's say you quit your job with money in the bank, you try, and you fail. You'll probably have to go back to a job or take freelance contracts, and you've spent the money in the bank on starting a business AND paying your nut while you do so, and you've got little to show for it. Why not fail while you've got a safety net (job)? Why not quit your job when you know you've answered the questions that need to be answered?
I know cuz I did this, and dealt with this very situation. It sucks and it slows you down. Ended up taking a job anyway. Think long term.