I was searching for some ancient quotes describing the same sentiment and found a page with several quotes, including this one from Aristotle (4th century BCE):

"[Young people] are high-minded because they have not yet been humbled by life, nor have they experienced the force of circumstances. ... They think they know everything, and are always quite sure about it."

https://history.stackexchange.com/questions/28169/what-is-th...