Confirmation bias is an extremely common problem especially for first-time founders. If you're unfamiliar with the term in this context, I'm referring to founders' tendency when speaking to customers to try and look for affirmation of their "good idea" rather than seek out the objective reality. Founders will essentially spend the entire conversation trying to convince the customer that they have a brilliant idea or worse yet that the customer has a problem that they don't. Whether consciously or subconsciously this happens a lot. This is the first layer of confirmation bias. With enough practice, many founders are able to push past it but even if they do their problems aren't over yet.
There is also a second layer to confirmation bias. The second layer is what happens when a founder is in a conversation with a customer and rather than the customer telling them that they don't have that problem or don't like their idea, they instead have an all together different perspective on how the product can be valuable.
Here's a made up example for how this might play out. Let's imagine you developed a mobile app for restaurants that allows patrons to order food and make payments directly through the app. You're initial hypothesis is that it will reduce the amount of time and interaction required by waitresses. After a few conversations with restaurant owners you come to find out that they could care less about the waitresses' time. They're more interested in the fact you can push promotional notifications through the app that will make patrons purchase more drinks and appetizers.
Unfortunately, many founders will hear that response and allow it to go in one ear and out the other. They will continue to press the customer on the benefits of saving the waitresses' time even when the customer told them point blank that, that is not their problem!
Stop trying to sell the customer what you want to build and start selling them the product they actually want. No one is interested in helping you confirm your own biases. People are interested in sales so stop resting your future on whether or not your initial idea is any good and start closing sales. If the restaurant owner says, "I'd love to see if we can use this to increase the number of drinks and appetizers customers buy." Your response shouldn't be "Well what about saving the waitresses' time?" it should be "That sounds great! How about we setup a pilot this Saturday night to prove out the results. If we can increase the average customer's sales by 10% would you be willing to sign up for our $X/month subscription?"