We will never lose all the knowledge we have. I can produce clean drinking water. I can build a combustion engine given enough time. I can build a multi story building. Africans still cant do that shit on average. I understand the physics underlying flight and could build a glider. I could build a gun. I could build a drill and saw to build a more precise drill and saw to be able to start machining things with accuracy. A group of people like me will, given time, ALWAYS dominate a group of stupid people. In a bad moment, caught alone, perhaps not. But thats just one little outlier.