There were those set on pushing forward their own particular set of ideals. Paul is trying to teach the boasting members of the Corinthian fellowship that charity is always modest, as Christ was modest. True charity is happy to serve even without reward. Some of the Corinthians were arrogant, full of themselves. Verse five begins with this fourth danger, directly tied into the third, and if only the Corinthians would learn to be charitable toward one another, they would be rid of their arrogance and its accompanying rudeness.
Selfishness is the opposite of charitable love.
The opposite of selfishness is not despising oneself, but love. One must love oneself before one can love one's neighbor. God is love. By not being provoked, the Christians at Corinth might suppress the evil that others might bring out in them. Neither is charity happy when someone does wrong.