“The problem with experts is that they do not know what they do not know.” ― Nassim Nicholas Taleb, The Black Swan: The Impact of the Highly Improbable.
The ‘knowledge we think we have’ is only .099% (a hypothetical figure to give you a mathematical idea, and pretending to be rational) of what originally exists in any given field. Even then we call some people experts in it as they know better than us. It is the relative knowledge that matters. Not the knowledge in itself. The relative knowledge sold well is the knowledge celebrated by the market. The popularity of what you know makes more money than the depth of knowledge.
90% of all existing knowledge in the world got upgraded in the last 10 years. Be it coding or genetics. If someone missed this, they are as ignorant as a layman.