Because you can not eat it, wear it, buy it, sell it, or have sex with it; wisdom has little value to the North American mind.
We forget, that all the highest experiences are feelings, invisible, non-material. Hope, Love, Respect, Integrity, Trust, Compassion, Empathy, Confidence, Self Worth. None of these can be held in our hand, weighed on a scale, packed in a box, or saved in a drawer for later.
We must remember that every time our ego wins, our soul loses.