Whether you should quit or not depends on (a) whether your idea has any potential and (b) whether you're suited to starting a startup. It's hard to tell either of those from your question.

The question I'd ask is, why did you start working on this idea? Was it something you yourselves needed? Or was it a made-up idea, meaning something you assumed other people wanted (but that perhaps they don't actually)?

If the answer is the former, focus on the problem you know exists from your own experience, and find the people who desperately need it. If you did, there must be others.

If the answer is the latter – that you're making something you hoped and predicted other people would want – then you're basically casting about at random. And though I resist ever advising people to quit, if there's a time to, that's it.