Do you really understand what all of that entails, all the grief and the sorrow and the pain, the agony of what He was going through? Do you really, really understand what it takes to sit on the right and the left side of Jesus? How do you get to that position?
This is another one of those very clear statements about His purpose. It may be the most direct statement of His redemptive purpose in the Gospels. What He does here in this passage, and that is why I read all of that from verse 20 on, is He connects high position, or leadership we might say, with service and sacrifice, using His own example of giving His life for a ransom of many as the prime illustration of what that looks like. It is far more than kneeling down and washing your brothers' feet. Jesus served and sacrificed, showing His leadership by dying the most despicable, bloody, agonizing death that you can imagine.
We have a contrast here between what is normal for the world—that is, abuse of rulership—and also what is normal for the Kingdom of God. What we see for the Kingdom of God is an entirely different attitude in the ruler. The one uses his power, to its fullest extent, to serve himself. The other uses his power first to serve God, and in serving God, he becomes the servant of the governed. That is not directly stated, but it is implied.