We have nothing that hasn't been given to us. And we should live like that. Instead of thinking highly of ourselves, as though we earned something or deserve something, we should all realize what we have has been given by God. In 1 Corinthians 4:6-8 Paul continues his rebuke toward those who were self-satisfied because they believed they'd reached some level of spiritual greatness(like in 1 Cor. 1:10-17). He asked them this questions, "What do you have that you did not receive?" to point out that God gave them everything they had.
Verse 8-10 is where it gets a little more my style. Paul get's sarcastic with, what the John MacArthur Study Bible calls, false praise. He tells them, "Already you have all you want! Already you have become rich! Without us you have become kings! And would that you did reign, so that we might share the rule with you!" Paul goes on to call himself a fool and the church at Corinth wise, as though he was mimicking the attitude of the proud Corinthians towards him.
Now, I don't want to pretend that I translated and explained this passage as I usually try. I was a little confused by most of 8-10 because I didn't realize that Paul could be sarcastic. But it makes more sense if it is read this way, and that's why I believe the John MacArthur explanation is valid (that and Johnny Mac is a great expositor of the word and has great men working with him). The point is to be humble in our lives. I know I'm not. I even think that God allowed an error at work to humble me a little because I was getting too arrogant in my own abilities. We need to take this humble path and realize all we have comes from God and Christ crucified.
Praise God for His Son.