Charles Darwin noted “Ignorance more frequently begets confidence than does knowledge”
Nobel prize winning psychological analysts defined what is known as the Dunning Kruger effect …
“The Dunning–Kruger effect is a cognitive bias in which the unskilled suffer from illusory superiority, mistakenly rating their ability much higher than average. This bias is attributed to a metacognitive inability of the unskilled to recognize their mistakes” See here for more
So if you are an entrepreneur in an area that you have no prior experience or domain knowledge … remember there is an irony in “believe in your self … believe in your idea“.
Account for a learning curve … surround yourself with sources of learning (customers, advisors, field research etc.)