Question

Why does ptah-hotep think it is a good idea to try to learn from everyone ignorant or learned

Answer 1

To learn from their mistakes so they can't do it again

Answer 2

Ptah-Hotep was an ancient Egyptian vizier, his intention leaving these ¨Proverbs¨, were mainly to teach and serve as guide to his son.

So basically he intended to difference these two kind of ¨mind states¨ (ignorance and knowledge), to learn and follow the example of the wise, and to avoid the mistakes and actions of the ignorant.