This verse is a thermometer of wisdom. It doesn't measure how much we know, but how teachable we are.
"Whoever loves discipline loves knowledge": Loving correction (discipline, feedback, instruction) is the shortcut to knowledge. Why? Because it's an act of humility that puts growth above comfort. Correction is the pain that produces learning.
"...but whoever hates correction is stupid": The "fool" here is not the one who makes mistakes; it's the one who hates being corrected. They are so armored by their own pride that they become impossible to help. They are the full cup that can receive nothing new.
"The Knight in Rusty Armor" — Robert Fisher
This verse is the summary of the book. The Knight hated correction (from his wife, from his son) and, because of that, remained a "fool" trapped in the armor of his ego. His journey of freedom only began when he humbled himself and came to love correction (from the blacksmith, from Merlin, from pain).
"The Root of Rejection" — Joyce Meyer
Why do we hate correction? As we read in this book, we confuse correction with rejection. We think "what I did is wrong" means "I am wrong." The person healed from rejection is able to separate the act from the identity.
The New Testament is clear: correction is the language of God's fatherly love. Hebrews 12:6 says: "because the Lord disciplines the one he loves, and he chastens everyone he accepts as his son."
If we hate correction, in practice we're hating the very tool God uses to shape us. The Pharisee hated Jesus' rebuke; the sinner (like Zacchaeus) loved correction and found salvation.
The central point is this: when we understand our unconditional acceptance in Christ, correction loses its power to make us feel rejected. Because we are already fully accepted in our identity as children, we can finally accept correction in our behavior, knowing it is for our good, not for our condemnation.