Mark 10:31

“But many that are first shall be last, and the last first.”

Finally Jesus ended by warning them against presumption, and no doubt Judas was especially in mind. Whether this means first in status and priority, or first in time, the same applies. It was possible to lose the benefit that was theirs. They could finish up last. Each must ensure his continuation in faithful service if he was to receive the prize (1 Corinthians 9:27). And it applied not only to them but to ‘many'. And in a sense the discouraging thing is that many who were first  will be  last. It was not to be seen as theoretical but as fact. Many would lose what they had at first gained. But it was also an encouragement. Those who were last need not despair, for they too could finish up first. It is never too late to begin to serve God faithfully.

Some would relate those ‘that are first' to the leaders of the people, or to the Pharisees, or to rich and important men in contrast with the common people and the poor. But in this immediate context this seems doubtful. What He has in mind here is for them not to lose what they have already gained.

Once again we should note overall that Mark presents his material in order to bring out Who Jesus really is. He is One Who can be called ‘Good' (Mark 10:17), an attribute reserved for God. He can demand that a man sell all he has and give it away to follow Him (Mark 10:21), promising eternal life on that basis. He can guarantee to His disciples that they will receive eternal life and share in the Kingly Rule of God (Mark 10:30 with 23) because of what they have done with regard to Jesus Himself. Jesus is putting Himself in the place of God.