The money is coming out your pocket, and you're losing more money as time goes by. You're stressed out about that, and trying to save money. So you're trying to find the cheapest developers you can, and the candidates that are ok with you're low ball salary are those without a lot of options (ie: unqualified, inexperienced, etc). But the good developers, they want real money (which you've misinterpreted as "fuck you, pay me").
Look I run a self-funded startup too.. and people are expensive. I get it. But it's a market. Those good developers aren't refusing to work for you because they don't want to work for anyone. They're refusing because they can get other offers. Your low salary offer isn't interesting to them.
It's as simple as that.