I gave more thinking to this last year, and asked myself what I could do to change this.
So we moved to a cheap place with the whole family, here we're able to buy a house without mortage (before the move it would have required 25/30 years mortgage + 2 high-paying jobs, to get something that wasn't even close in term of quality/space).
Here goes the rent :)
This is pretty much what I did, I saved money and now don't have to worry about contracts or client work, I can focus solely on the company and keep costs down as if I had taken outside investment.
YC never really entered the conversation for us, I view YC as a place for people that fall into a "I have this idea I want to try, but if I quit my job I can't pay rent" type category, which wasn't me or the people I'm working with.
(edit to say that I'm not knocking the stated category, I'm really happy that YC exists)
But if you can overcome these obstacles using proper time management, project scheduling and keeping fixed costs to a minimum, you'll end up with significantly greater equity and fewer fingers in your proverbial pie, in contrast to giving up equity and answering to your investors, however useful their input may be.
Bootstrapping a startup requires you have a real-world business model which actually generates revenue, which is more than many investor-backed companies can say. However, a profitable model is not necessarily a sustainable one. You could fill your schedule with client-contracted work and pay the monthly overhead and maybe yourselves too, but it's not the most sustainable long-term business strategy (unless you really want to be doing this forever.)
So you contract/consult to pay the bills, at the same time devoting a reasonable portion of your time to building your own products and looking for your "homerun."