No one person knows everything there is to know about something. Even the best of them do not. However, how they bridge that gap is by first acknowledging the areas that they are lacking and source for external help and support. These successful people even go to the extend of getting a coach to get them to the ‘next level’. You probably would not read or hear about that but they often do, might not be a coach per se, perhaps an advisor or a mentor.
The rule of thumb here is to identify the areas that you are lacking and are in need to get you to where you want to be and be brave enough to get support for it.