The problem is surface knowledge is blown away easily, like topsoil. However, most people are operating on the same level of surface knowledge! So, in a twisted bout of game theory, we are rarely if ever called out on our bullshit (because people fear that we’ll call them out on theirs.)
In other words, past confidence will only take you so far. If you rely too heavily on prior experience and stop pushing new boundaries, you’ll get stuck. Eventually, everything will start crashing down. Because to maintain confidence, you must continually be growing. You scare confidence away by trying to maintain the status-quo. Confidence, by nature, requires that you take bold new risks to seek new growth and opportunity.