Even though I already answered "every" one I could find -- I wonder if this one in particular is the one you are most concerned about?
As I was just saying above, full total context. (That's the way His Words work: as full complete teachings, for those willing to listen and hear.)
Let's look:
--------------
16 Just then a man came up to Jesus and asked, “Teacher, what good thing must I do to get eternal life
17 “Why do you ask me about what is good?” Jesus replied. “There is only One who is good. If you want to enter life, keep the commandments.”
18 “Which ones?” he inquired.
Jesus replied,
“ ‘You shall not murder, you shall not commit adultery, you shall not steal, you shall not give false testimony, 19 honor your father and mother,’ and ‘love your neighbor as yourself.’ ”
20 “All these I have kept,” the young man said. “What do I still lack?”
21 Jesus answered,
“If you want to be perfect, go, sell your possessions and give to the poor, and you will have treasure in heaven. Then come, follow me.”
22 When the young man heard this,
he went away sad, because he had great wealth.
23 Then Jesus said to his disciples,
“Truly I tell you, it is hard for someone who is rich to enter the kingdom of heaven. 24 Again I tell you, it is easier for a camel to go through the eye of a needle than for someone who is rich to enter the kingdom of God.”
25 When the disciples heard this, they were greatly astonished and asked,
“Who then can be saved?”
26 Jesus looked at them and said,
“With man this is impossible, but with God all things are possible.”
27 Peter answered him,
“We have left everything to follow you! What then will there be for us?”
28 Jesus said to them,
“Truly I tell you, at the renewal of all things, when the Son of Man sits on his glorious throne, you who have followed me will also sit on twelve thrones, judging the twelve tribes of Israel. 29 And everyone who has left houses or brothers or sisters or father or mother or wife or children or fields for my sake will receive a hundred times as much and will inherit eternal life. 30 But many who are first will be last, and many who are last will be first."
Matthew 19 NIV
[underlining added]
------------------
It can be a full meal already just to listen to something Jesus says, but if you wish to hear my understanding also, here it is (or you could come back later to see it) --
The rich young man faced, with a choice of his wealth and following Christ (literally here, since Christ is literally in front of him), chose to remain/dwell/stay with his wealth, instead of following Christ and thus leaving his wealth behind.
Illustration from another moment on the very same question --
19 Then a teacher of the law came to him and said, “Teacher, I will follow you wherever you go.”
20 Jesus replied, “Foxes have dens and birds have nests, but the Son of Man has no place to lay his head.”
Matthew 8 NIV
See what following him literally meant there: traveling from place to place, without a home, wealth, luxuries...literally sleeping on the ground out in the open often enough.
Which is more important to us? -- our preoccupations/luxuries/hobbies/interests/pursuits/clubs/politics/etc. ... or... following Jesus, by listening to Him and hearing Him and then doing as He says? Which is the priority and first choice, for a person?
What comes first in your life? Unless the Lord is first, then whatever you put first is your true 'god'/'idol'.
Here's that same lesson again --
19 “Do not store up for yourselves treasures on earth, where moths and vermin destroy, and where thieves break in and steal. 20 But store up for yourselves treasures in heaven, where moths and vermin do not destroy, and where thieves do not break in and steal. 21 For where your treasure is, there your heart will be also.
22 “The eye is the lamp of the body. If your eyes are healthy, your whole body will be full of light. 23 But if your eyes are unhealthy, your whole body will be full of darkness. If then the light within you is darkness, how great is that darkness!
24 “No one can serve two masters. Either you will hate the one and love the other, or you will be devoted to the one and despise the other. You cannot serve both God and money."
Matthew 6 NIV
He says, and I hear Him, that I cannot put money first and still follow Him. He has to be first (and money only a mere tool and not first.)
Now as we can see above, the rich young man truly treasured his luxuries/wealth. They were first, for him. Even above the chance to follow Christ in person.