The ability to focus, carry a project through, and teach yourself should be built by about age ten, not purchased at twenty-two.
This idea is shared between Four Weeks, Not Four Years and Sui Learning, Trenton Rich's book on teaching children at home. The full entry, with the evidence and sources, lives with the homeschooling method at suilearn.ing.
In Four Weeks, Not Four Years: Chapters 2 and 9.