I also tend to fall into this trap telling myself that I know everything about the subject as well. But then I realise that we need to keep an open mind to see other points and other opinions, otherwise we are just stuck in the same place. I think to remain openminded in this sense gets more difficult with age LOL
Reading your lines, I got on my mind one interesting saying about the cryptocurrencies from one of the blockchain conferences where I was...
"Bitcoin private keys are impossible to "de-crypt", or to hack.... YET..."
The same goes for knowledge... Maybe we think that we know it all, but it's always can be something more, or something new, that we didn't hear about...
That's a good analogy. We should always be interested in the "thing" that will decrypt the impossible :-)