I agree with you. The wizard has it backwards. He's not Glenda the Good after all. He's a charlatan, a poseur, a fake, a fraud, and his worldview is that which has perennially been held by such people.
In Baum's day, not every character in children's books had to speak virtuously or truly. Children in those days could apply critical thinking skills, and clever authors like Baum and Lewis Carroll often challenged them to do so. This was not considered corrupting children but rather strengthening them and preparing them better for life in the big people's world.
The wizard is no hero, or model. He is a pathetic figure, and an anti-climax at the end of the Yellow brick (gold bullion) road that Dorothy walks with her silver slippers.
You correct me now and tell me they were ruby slippers, and I retort the first edition says silver.
Anyhow gold and silver get you to a place where it's the love tribute you receive that counts not the love fountain bursting outward from your heart. Your main capacity is to receive, not to act. Love is action of the highest quality.
My eyes, my mind, my heart