I'll add that I think there is also a psychological element that's easy to overlook. As much as we often fear talking to customers, we're human, and we're built to need interaction with other humans. Trying to build software in a vacuum is really hard for technical and business reasons, but it's also less rewarding psychologically. Most of the entrepreneurial types on Hacker News are not just trying to build a cool app or a great business, we are trying to add some small bit of meaning to the world. Talking to customers helps connect with that meaning (even beyond the satisfaction of customers using your product).
I'll add that I think there is also a psychological element that's easy to overlook. As much as we often fear talking to customers, we're human, and we're built to need interaction with other humans. Trying to build software in a vacuum is really hard for technical and business reasons, but it's also less rewarding psychologically. Most of the entrepreneurial types on Hacker News are not just trying to build a cool app or a great business, we are trying to add some small bit of meaning to the world. Talking to customers helps connect with that meaning (even beyond the satisfaction of customers using your product).