The biggest blind spot for any company is the 'curse of knowledge'.
Presumably, our companies are started because we felt so strongly about a problem; a void that we have a unique approach to solving and we do. Doing it over years, make us the experts and arguably so.
With expertise comes the curse of knowledge.
"The curse of knowledge is a cognitive bias that leads better-informed parties to find it extremely difficult to think about problems from the perspective of lesser-informed parties."...