Context is important here, as is the internal attitude of the characters that Jesus describes. Repentance is a key theme in the case of Zacchaeus, and it is missing from the other two stories. Also Zacchaeus differs from the Rich Man in Matthew because of his age and social responsibilities. God does not expect everyone to sell all they own, but we should make devotion to God our top priority.
The Rich Young Man and the Rich Fool
The rich man in Mt. 19 was a Rich Young Man. This implies he did not yet have major social responsibilities. When Jesus told him at first what was needed to inherit eternal life, the young man reported "all these I have observed, what more do I lack?" I interpret this to suggest that the young man was a searcher, even a candidate for discipleship. But he did not demonstrate humility or repentance. When Jesus informed him that he would first need to sell all he had and give it to poor, the young man could not rise to the challenge.
Discipleship is also the context of the parable of the Rich Fool. It does not deal with an actual person, so Jesus is able to use hyperbole to make his point, that when all is said and done, riches avail us nothing. The parable serves as a foundation for a lesson which is directed toward his disciples, not the general public:
And he said to his disciples, “Therefore I tell you, do not be anxious
about your life, what you shall eat, nor about your body, what you
shall put on. For life is more than food, and the body more than
clothing. Consider the ravens: they neither sow nor reap, they have
neither storehouse nor barn, and yet God feeds them. Of how much more
value are you than the birds!"
This does not mean that everyone must live without planning for tomorrow. But it does show how Jesus expected his immediate disciples to live at this particular moment in providential history. For general purposes, it teaches that we must trust God absolutely, not that we should live without homes or possessions as the first disciples did.
Zacchaeus was a different case. He was neither young, nor a searcher, nor a candidate for full time discipleship. He was a householder and well established in his community as a tax collector. No doubt he also had to support a family. He apparently had not obeyed the Golden Rule as the Rich Young Man had, but changed his ways and resolved to do more. Repentance is a key factor here. Because Zacchaeus repented, giving half of his possessions to the poor was sufficient. He was not qualified to be a core disciple but he could help Jesus in other significant ways.
In addition, the two incidents that involved real people teach different lessons. In the case of the Rich Young Man, the lesson is that even a person loves God and obeys the Golden Rule still needs to be humble and do more. In the case of Zacchaeus the lesson is that God accepts sinners who repent. The story also teaches that those who judged Zacchaeus are wrong: "He too is a son of Abraham... The Son of man came to seek and to save the lost."
Conclusion: Some may indeed be called to do give up everything to follow God, but such cases are rare. However, everyone does need to repent and make devotion to God their top priority. If we do so, we avoid the fate of the Rich Fool. We also need to avoid the attitude of Zacchaeus' neighbors, who judged him because of his profession and even criticized Jesus for dining with him. God does not want everyone to give up all their wealth.