From First Corinthians by George T. Montague, SM, commenting on I Corinthians 3:16-23
[C]oncluding that no one should boast about human beings (the different ministers), he suddenly adds his own theological insight: Everything belongs to you, he begins, applying this first to the ministers, Paul or Apollos or Cephas. The Apostle here reverses the logic of the Corinthians. They had said that they belong to one or the other minister, as if that gives them their identity, their importance. Not so, says Paul. The ministers belong to you—all of them. The ministers belong to the people, not the people to the ministers. The ministers are servants, not captains of competitive teams. And they are servants of everyone.
That is clear enough. But Paul had said everything, not everyone belongs to you. And now he goes on to list those things as the world or life or death, or the present or the future: all belong to you. What does he mean by this, and what does this have to do with the problem of rivalries? When one feels the need to boost one’s ego, one grasps at things that will give one the sense of importance, such as whose coattails do I claim to ride on?
But Paul senses that the grasping for identification with one leader over another is symptomatic of a much deeper human compulsion to possess, to pad one’s security with ownership of things, even of persons like Paul, Apollos, and Peter. Paul wants to convince his people that belonging to Christ has set them free from those compulsions if they will but claim that belonging. This is similar to Jesus’ teaching that those who seek first the kingdom of God will attain everything else besides (Matt 6:33).