Let's look at the context before the quote too: Mark 10:17-27 (NLT)
> As Jesus was starting out on his way to Jerusalem, a man came running up to him, knelt down, and asked, "Good Teacher, what must I do to inherit eternal life?"
> "Why do you call me good?" Jesus asked. "Only God is truly good. But to answer your question, you know the commandments: 'You must not murder. You must not commit adultery. You must not steal. You must not testify falsely. You must not cheat anyone. Honor your father and mother.'"
> "Teacher," the man replied, "I've obeyed all these commandments since I was young."
> Looking at the man, Jesus felt genuine love for him. "There is still one thing you haven't done," he told him. "Go and sell all your possessions and give the money to the poor, and you will have treasure in heaven. Then come, follow me."
> At this the man's face fell, and he went away sad, for he had many possessions.
> Jesus looked around and said to his disciples, "How hard it is for the rich to enter the Kingdom of God!" This amazed them. But Jesus said again, "Dear children, it is very hard to enter the Kingdom of God. In fact, it is easier for a camel to go through the eye of a needle than for a rich person to enter the Kingdom of God!"
> The disciples were astounded. "Then who in the world can be saved?" they asked.
> Jesus looked at them intently and said, "Humanly speaking, it is impossible. But not with God. Everything is possible with God."
Jesus's analogy about a camel going through the eye of a needle is commentary on the situation that he and his disciples just witnessed. The rich man thinks that he can earn his way into heaven through good deeds: he's asking "what must I do to inherit eternal life", and probably hoping for a pat on the back from Jesus for all the good things he's done. But instead Jesus identifies a much deeper issue in his life: his earthly wealth is more important to him than anything else, even his eternal destiny! The point of the camel analogy is that riches are a distraction that make it impossible to "love the Lord your God with all your heart, all your soul, all your mind, and all your strength."
> Surely from what he's said it's obvious that poor people can be saved. And when Jesus says 'for God all things are possible', isn't he implying that some rich people might get into heaven? So why do people interpret the passage as Jesus saying this is impossible?
The central point of the Bible is that there are no "good people". Everyone is morally corrupt in one way or another, and cannot be saved through their own effort, only through Jesus's sacrifice on the cross. "God saved you by his grace when you believed. And you can’t take credit for this; it is a gift from God. Salvation is not a reward for the good things we have done, so none of us can boast about it." (Ephesians 2:8-9, cf. Romans 3, Psalm 14, John 14). A lot (most?) of Jesus's teachings, including the passage in the OP, are addressed to people who think they are "good enough" and showing them to be self-righteous, hypocritical, and in need of salvation just as badly as everybody else.