In my personal experience, people don’t live in reality. They live in what they want or imagine reality to be. If you ask many people what they think is going to happen regarding something important to them, it’s difficult for them to say “I don’t know”. That might in their opinion make them appear incompetent. It’s more likely that they’ll tell you something about what they are telling themselves is true. They may indeed be telling themselves something true, but with all our motivated reasoning, humans find this difficult. This means that normal people (myself included) could very well be wrong about a lot more topics than you think. It also means you are likely to underestimate how wrong somebody might be, if you’re the sort of person who wants to see the best in people.
We’re drawn to confident people, so it’s hard to accept ignorance. But, as I see it, it’s potentially a sign of competence to admit when you don’t know something. You have to be pretty knowledgeable about stuff in order to know what you don’t know. And once you are comfortable with your ignorance, you’re also much more comfortable saying “I don’t know” when somebody asks you a tough question. IDK is the starting point of knowledge. It’s ok.