I really think the big steps forward come from people who have thought deeply about the challenges and are just as passionate about overcoming those challenges, not from people who weren't aware of the challenges going into it that didn't know how hard the thing they were trying to do was.
It's the difference between the George Hotzes of the world and the people who actually do the boring hard work to push through obstacles and make things happen. A George Hotz is a person who doesn't know what they don't know, and therefore gets their inspired, genius projects completely derailed by trivially avoidable, trivially predictable stumbling blocks, because of their overconfidence and lack of intellectual maturity. A not-George Hotz is someone who is probably a lot more boring to watch on YouTube, but is equally inspired and passionate. They obsess over potential obstacles far more than they talk about how awesome their project is going to be when it's done, and how confident they are in its success.
Depends. Is that `someone` the future employee or investor that would otherwise have played a critical role in the company achieving this task?
My point is that disbelief can stop the right person from taking the right action the company needs.