The question is not how far along you've come with the existing stack, it's how far you're going to get with the existing stack. Is the development stack the right one to get you to a stage where you can get outside investment? If it is, you need to make a hard choice: Are your current developers the right team to get this product to that stage? If they are, suck it up and get on with it. If not, you need to consider the hard decision of replacing them.

I can't speak to your team's competence (like a previous poster suggested) - everyone has their own situation. I'm working with a talented development team on a startup right now and I can tell you something for nothing, we're a few months in still analyzing what needs to be done and which stack is the most appropriate for that. None of us shy away from learning new technologies and all appear to have a knack for it. We've all got full time jobs and families and none of us are betting the farm... yet, we're quietly confident but it's early days. It's okay to be hungry and to believe in your dream, but leaving your family holding the bag to support that dream is not right in my mind. There will be many that will find ways to reframe this statement and disagree, but that's my bottom line.

Don't believe that because your previous CTO decided on the stack that you're stuck with it. If you can get something to market quicker and easier by changing stack and you're not sacrificing anything except the skillset and ego of the previous CTO, do it - but don't do it just because you don't have the skillset of the previous CTO.

If you've got less than no money and you're living out of your car, but you have food on your metaphorical table, then it seems to me you're not losing that much.

Not changing because "it's more work than it's worth" is not good advice because it's subjective - if you gain a product by changing and don't have a product by not changing, then it's worth it. This is your baby, not your developers; make decisions from a business perspective with the technical understanding of a developer. don't make them from a developer's perspective - never lose sight of the big picture.

What is your idea worth? $100,000? $1M? $10M? $100M? 100% of nothing is nothing - which is what you're going to get if you give up or let your developers stall your idea from getting to market. You will have incurred debt and the hardship of living out of your car. So you will have actually made a loss. Do what it takes to get your product to market on your terms, not someone else's. If that means changing stacks, change stacks. If that means sticking it out with your current stack and sucking up another couple of months of living in your car, that's okay too. Equally, don't be scared to give up because you've hit your limit. We all have limits and only you can decide what those limits are for yourself.

Don't fail because of someone else's suggestion. Fail because you tried every avenue you could see and couldn't find a way to overcome the obstacles on those paths... and then when you "fail", stop, reflect, analyze, figure out where you think you went wrong, figure out how you could have overcome the problems and go at it again with a new perspective. If that means putting the project on hold for a few months while you get a job and dig yourself out of your hole for a few months, do it. If it means cutting back to part time so you have money in your pocket while you build, do it. If the project is worth what you hope and dream it is, don't give up on it. Just find a more sustainable approach to get it out there.

This may be your only chance to make your own meaningful contribution to the world. Giving up on that is like giving up on the meaning of life itself... is that more or less scary than being in debt and living in your car?