This quote is saying that it is better to gain wisdom than to gain wealth or possessions. “Don’t gain the world” is a reminder that possessions won’t bring true happiness or fulfillment. Instead, it is better to focus on gaining wisdom, which will enable you to make good decisions and live a life of meaning. It is saying that you should not focus too much on money and material possessions, as these will not make you truly happy. Wisdom, on the other hand, will give you the ability to make wise decisions and live a life that is full of purpose and deep meaning.