The onlookers see clearly
As the saying goes, "the onlooker sees clearly when he is in charge of the game", it means that the party involved in a matter often does not have a comprehensive understanding because he considers too much about the gain and loss of a thing, but is not as clear as the onlooker. It comes from the biography of yuan Xingchong in the old book of Tang Dynasty.
source
Liu Xu's the old book of the Tang Dynasty, the biography of yuan Xingchong, in the later Jin Dynasty: "the authorities say that they are confused, and they will see the trial by the side (side)
Examples
It can be seen that "those who are in charge of the game will see clearly.
The onlookers see clearly
get the opposite of what one wants - yù yì fǎn bì
insatiably covetous and gluttonous - tān lán wú yàn