following the road of gold leads eventually only to the Emerald City, which Taylor sees as symbolic of a fraudulent world built on greenback paper money, a fiat currency that cannot be redeemed in exchange for precious metals.[11] It is ruled by a scheming politician (the Wizard) who uses publicity devices and tricks to fool the people (and even the Good Witches) into believing he is benevolent, wise, and powerful when really he is a selfish, evil humbug.

https://en.m.wikipedia.org/wiki/Political_interpretations_of_The_Wonderful_Wizard_of_Oz