The disciples seemed to live one day at a time with little thought of the future, except they felt that Jesus would be great, and they would have important roles (Luke 9:46).  They did not understand that He would leave them to finish the work of establishing the church under the direction of the Holy Spirit.  They would be 'put in charge' of the church and prepare the generations of believers to eagerly anticipate His return.

They had started to understand that Jesus was training them and that the parables and miracles were not just for the benefit of the crowds or favoured individuals.  It was all to equip them for the task of church leadership - a job for which many of them would be martyred.  In these verses, Peter was starting to connect that these leadership tutorials were not just interesting stories for the crowd, but specifically aimed at him and the other disciples who had been appointed as apostles (Luke 6:13-16).

But to be given that responsibility was a huge step in their thinking.  Yes, they were hungry for power and greatness but the responsibility which was given came with accountability (Matthew 20:20-28).  Jesus was giving them the gospel keys of the Kingdom (Matthew 16:19) and the people who would be brought to faith by believing it ... and the sense of responsibility was slowly sinking in.

Everybody who belongs to Christ has a spiritual responsibility to the people around them.  The days of foundational church leaders have been completed, but every Christian parent is a pastor-teacher and evangelist to their family.  Every believer is a prophet with the responsibility to say what is true about the covenant of God's grace.  Every compassionate soul can only function if the Holy Spirit is allowed to stir up faith and good works.  As Jesus said, "From everyone who has been given much, much will be demanded; and from the one who has been entrusted with much, much more will be asked." (Luke 12:48).  The Christian who enjoys the blessings of God and has no sense of responsibility to work for Him is like a child playing with tools as though they were toys.  No, we are all responsible and therefore accountable when Jesus returns.  Firstly, this is a matter of confession and prayer, then we need to face our responsibilities as seriously as we shall face Jesus on the day He returns.