If you are running a startup, you must be selling something. It doesn't matter if it is a product or service, b2c or b2b, you are spending your energy and effort to sell stuff. But how do you answer the question: What are you selling? The way you think about those lines to reply it are extremely important because you don't sell stuff, you must sell value.
You must sell value because that's what people buy. As Simon Sinek explains with the golden circle, at his book "Start with why", which, by the way, I strongly recommend. When you have a purpose, you are closer to build something with value. As he quotes:
“People don't buy what you do; they buy why you do it. And what you do simply proves what you believe.”
Since every startup must start from a problem, is the problem you want to solve important to anyone? That is an important question, because sometimes you may be resolving really well someone's issue, but is it relevant? If you solve a real problem, but low value, people will still use your solution. The problem is it might not be sustainable because you are not creating value and it cannot create sustainable revenue.
People are willing to use anything that makes their lives easier. On the other hand, you need cash to survive. You may question that some companies, such as WhatsApp, does not make money and despite that, it was worth billions of dollars. That's true, and the point is: generating revenue is not the only value you can create, but a revenue stream is a sign that someone sees value in your solution.
Money has value, data has value, the time has value. The equation you must solve is about how much of it can deliver to your customers. My advice here is to start finding where is the value at the problem you are addressing. After that, you start thinking about your solution. In the end, if the product or service ready to market, never stop thinking about how to add value to it.