Armchair Quarterback
Fleeting- Référence externe : https://www.languagehumanities.org/what-is-an-armchair-quarterback.htm
An “armchair quarterback” is someone who offers his or her opinion on something without actually being a part of it. It is an idiom that has branched out from the sports world to encompass many other aspects of life.
— https://www.languagehumanities.org/what-is-an-armchair-quarterback.htm