The Spiritual Principles of the 12 Steps of AA explains why Humility is the Spiritual virtue of Step 7.

Step 7. Humility: Not proud or haughty; not arrogant or assertive; a clear and concise understanding of what we are, followed by a sincere desire to become what we can be. Humility is the evidence of our trust in God.

Pride leads to disgrace, but with humility comes wisdom (Proverbs 11:2 NLT).