There are many even today who casually use the word "good", but no one is good except God alone. And since that is the case, then inheriting eternal life cannot be a function of whether one is good, else no one would inherit eternal life. But this man seemed to think he could inherit eternal life by "doing" something. And there are many of those who seek God today who ask the same thing of God - "What must I do to inherit eternal life?" Even the Evangelical community has often answered in inappropriate ways focussing on some technique like praying such and such a prayer or joining a church. But inheriting eternal life is not a matter of doing something, but of believing in Christ.
John 6:And the Bible indicates that faith is not a work.
28 Then they asked him, "What must we do to do the works God requires?"
29 Jesus answered, "The work of God is this: to believe in the one he has sent."
Rom 4:4,5 Now when a man works, his wages are not credited to him as a gift, but as an obligation. However, to the man who does not work but trusts God who justifies the wicked, his faith is credited as righteousness.Yes, the faith is an application oriented faith, but the object of faith is Christ, not one's own works.
The problem this man had was that he didn't reckon himself a sinner and so was not prepared for such faith. For faith in Christ includes not only faith in Christ as Lord, but also faith in Christ as Savior. But this man had yet to recognize his need to be saved from his innate sinfulness.
There are many today among the Christian community who reckon Christ as Savior, but not really as Lord - in practice. But this man was more along the legalistic lines, reckoning Christ more as Lord, but not as Savior. What should we do with such people? Perhaps we should do just what Christ did. We should convict them of sin. Yes, this involves humilating them - but that's just part of the ministry.
As when God leads the people of Israel out of Egypt to Mount Sinai, so Christ leads this man first to the Law. For "through the law we become conscious of sin." Rom 3:20 "So the law was put in charge to lead us to Christ that we might be justified by faith." Galatians 3:24 However this man was too self-righteous, reckoning only the letter of the Law and not its spirit, which was apparently a common attitude among religious Jews. For his greed was revealed when he was told to give away all the material things he had. Often we may not realize what idols we hold in our hearts until we are challenged to get rid of them. And it's easy for rich people to reckon themselves good. They may reckon their riches to be rewards from God for their own goodness. But the Bible says, "do you show contempt for the riches of his kindness, tolerance and patience, not realizing that God's kindness leads you toward repentance?" Rom 2:4 And James writes, "Listen, my dear brothers: Has not God chosen those who are poor in the eyes of the world to be rich in faith and to inherit the kingdom he promised those who love him? But you have insulted the poor. Is it not the rich who are exploiting you? Are they not the ones who are dragging you into court?" James 2:5,6
Such is characteristic of the rich. But one's innate sinfulness is more easily revealed in dealing with the troubles of life, which is why God led the people through the desert.
Remember how the LORD your God led you all the way in the desert these forty years, to humble you and to test you in order to know what was in your heart, whether or not you would keep his commands. He humbled you, causing you to hunger and then feeding you with manna, which neither you nor your fathers had known, to teach you that man does not live on bread alone but on every word that comes from the mouth of the LORD. Deut 8:2,3Humility is what this man lacked. Yet humility is the most essential of character qualities in that it leads to conviction of sin and repentance and a respect for God's Word. "This is the one I esteem: he who is humble and contrite in spirit, and trembles at my word." Is 66:2
It is such "good" people as characterized by this rich man whom Jesus finds it difficult to come to salvation. For they are not prepared to meet the acceptable criteria necessary to receive the gift of eternal life. And developing saving faith in them even God says is "difficult", though not impossible.