The issue for the disciples wasn’t so much that they were concerned about the salvation of others. They were worried for themselves.
They had just seen a man who seemed to meet all the requirements for heaven, according to their religion, be turned away by Jesus. He kept the commandments, and he was rich. The way they understood it, to be rich meant that God approved of you, which is why he blessed you.
So, if it was so hard for rich people to be saved – people who had God’s approval – what about them? The disciples were dirt poor. Jesus’ answer to them is straightforward: Salvation is impossible for men, but not for God. All things are possible for God.
“And they were astonished out of measure, saying among themselves, Who then can be saved? And Jesus looking upon them saith, With men it is impossible, but not with God: for with God all things are possible.” – Mark 10:26-27