What caused people in Jerusalem to change so much from "Palm entrance" to crucifixion day?

I have often wondered this myself but never really formulated a thoughtful answer. I have tried to search through various commentaries for an in-depth explanation and also to no avail. I put then the things that stand out to me as an explanation from the wider view of the gospel story.

Firs this is a key verse to have some context:

7 A man called Barabbas was in prison with the insurrectionists who had committed murder in the uprising. 8 The crowd came up and asked Pilate to do for them what he usually did. 9 “Do you want me to release to you the king of the Jews?” asked Pilate, 10 knowing it was out of self-interest that the chief priests had handed Jesus over to him. 11 But the chief priests stirred up the crowd to have Pilate release Barabbas instead. (NIV Mark 15:7–11)

Therefore we are not only dealing with a fade out of the Palm entrance cheers but a bloodthirsty crowd who chose a murderer over the ‘the Holy and Righteous One’. (Acts 3:14) Possibly the fact that Barabbas was an insurrectionist leads us to see why the chief priests were able to ‘stir up the crowd’ so effectively? In other words, was it not partly the expectation that Jesus was the King of David that led to the excitement of the crowds who received him with Palm branches? The very meaning of and use of the Palm branches was to proclaim royal victory (see Does ‘palm branches’ in Palm Sunday draw meaning from Jewish culture, or Greco-Roman culture that the Jews adopted?).

With an expectation of a warrior Messiah the excitement was for him, but with the clear denunciation of the Jewish leaders, his arrest and trial, how could this 'weak' Jesus be the insurrectionist they had hope for? Now the appeal to Barabbas who may have even been a kind of false Messiah, or at least more of the spirit of who they wanted as a Messiah, was empowered by the blunt contrast between them. Now it was easy for the Jewish leaders to garnish more and more frenzied support for their bloodthirsty cause. In addition, probably some of his followers could feel trouble in the air and withdrew as the crowd encircled their prey. The picture makes one think not only was the crowd under the influence of the Jewish leaders but all of them were brought into a state of frenzied demonic influence as the Devil was about to strike the heel of the child of the Woman, who would crush his head.

There are two obvious options - either they were the same people or they were not - with no supporting evidence for either. John Shelby Spong provides a third option that I find convincing. The story of the crowd welcoming Jesus into Jerusalem is closely based on a Jewish tradition that occurred each year, but at an entirely different time.

Spong says in Jesus for the Non-Religious, "The Jewish eight day celebration of the harvest, known as Sukkoth, and also called the Festival of the Tabernacles or Booths, was probably the most popular holiday among the Jews in the first century. In the observance of Sukkoth, worshippers processed through Jerusalem and in the Temple, waving a bunch of leafy branches made of willow, myrtle and palm. As they waved these branches in that procession, the worshippers recited words from Psalm 118, the psalm normally used at Sukkoth. Among these words were 'Save us, we beseech you, O Lord.' Save us in Hebrew is hosianna or 'hosanna'. This is typically followed by 'Blessed is the one who comes in the name of the Lord. (Psalm 118:25-6)'." Although the Passover is too early for leafy branches (except palms), Mark 11:8-9 says (NAB), "Many people spread their cloaks on the road, and others spread leafy branches that they had cut from the fields. Those preceding him as well as those following kept crying out: 'Hosanna! Blessed is he who comes in the name of the Lord!'." The Gospels of Matthew and Luke more or less follow Mark, but John's Gospel corrects this to say 'palm branches', creating our modern tradition of Palm Sunday.

Spong has identified the account as being a literary creation, in which case there is no meaningful answer as to whether they were the same or others.

He spent his time teaching at the temple.

Matthew 26:55 NKJV

In that hour Jesus said to the multitudes, “Have you come out, as against a robber, with swords and clubs to take Me? I sat daily with you, teaching in the temple, and you did not seize Me.

So most likely his followers where at the temple waiting for him to teach. And if his followers where at the temple, they where not at the Pontius Pilate's.

Matthew 27:2 NKJV

And when they had bound Him, they led Him away and delivered Him to Pontius Pilate the governor.

This is my logical deduction, yet specifically I do not know.

What caused the change from worshippers at Triumphal Entry on Sunday to haters at the passion? The answer is things changed over the four days.

They had known Jesus some 3 1/2 years. He had healed the sick, gave sight to the blind, walked on water, verbalized against the elders, and raised the dead. Jesus was the one. He was of the line of King David.

Took branches of palm trees, and went forth to meet him, and cried, Hosanna: Blessed is the King of Israel that cometh in the name of the Lord. John 12:13

And the multitudes that went before, and that followed, cried, saying, Hosanna to the Son of David: Blessed is he that cometh in the name of the Lord; Hosanna in the highest. Mat 21:9

Four days later, however, the authorities had arrested Him. Tried Him. Scourged Him. Sentenced Him to death. This was a complete and utter reversal of everything they had known and believed.

For centuries, Christians have explained about two comings as suffering servant and King of kings. No one saw that at the time. Indeed, it had been prophesied this would happen.

“Awake, sword, against my shepherd, against the man who is close to me!” declares the LORD Almighty. “Strike the shepherd, and the sheep will be scattered, and I will turn my hand against the little ones. Zec 13:7 and Mat 26:31

So, to answer the OP, those who cried out Hosanna, King of Israel, when the time was good, all departed when expectations were not met.

God is amazing in that He can have real people make real choices that have are rooted in metaphoric and spiritual meaning.

1.) It was the same people in that it was the nation of Israel who welcomed Him with much praise, and it was the same nation of Israel that demanded He be crucified. The thing to understand is that throughout all of their history Israel has been on a roller-coaster relationship with God. We see that in Exodus, Judges, Kings, all the prophets, and practically everywhere else in the Old testament. One generation praises God and is rewarded, the next generation loses it, gives in to idolatry and is punished. The amazing thing is that they do it over and over, the same mistakes time and time again. I would list references to exact passages but I'd take up the entire page with them. Here they simply were excited for God in that they thought this might be their "warrior king messiah" and when God's plan took a different direction they did what they do best. Turn away from God. Just like the Golden Calf in Exodus 32 and The idol worship detailed in Kings concerning the Prophet Elijah's constant battle with the false prophets of Baal.

2.) Understanding the biblical definition of "blindness" is key here as well. In John's Gospel chapter 12 it says,

37 But although He had done so many signs before them, they did not believe in Him, 38 that the word of Isaiah the prophet might be fulfilled, which he spoke: “Lord, who has believed our report? And to whom has the arm of the Lord been revealed?” 39 Therefore they could not believe, because Isaiah said again: 40 “He has blinded their eyes and hardened their hearts, Lest they should see with their eyes,Lest they should understand with their hearts and turn, So that I should heal them.” 41 These things Isaiah said when he saw His glory and spoke of Him.

Blindness was tool that God used over and over again to symbolize man's fallen nature. There was the messiah, God in the flesh right before them and they -could- -not- -see- -it! That was precisely the point though you see God's Will must and will always come to pass regardless of what scenario surrounds it. Just as the law required that the people of Israel sacrifice a lamb to God for the passover and for atonement for their sins. So to was the Messiah to be sacrificed. It had to be Israel who chose the death sentence despite Pilate's willingness to be merciful. If Jesus was never executed we the Gentiles would have no part in God's kingdom. We would not have Christ's remdemptive work to be our mediator to God.

3.) Israel was looking for a warrior king. Another David or something to that nature that would come and restore God's people to the position of power in the world. Their interpretation of scriptures called for that and they're still awaiting that today, which is why they, for the most part, will never accept Christ as the messiah until He returns. Fulfilling that prophecy just as the scriptures said he would. They were ignorant however that "The age of Grace" would come beforehand. How they missed Isaiah 53 & 54 I do not know but it's all pretty much detailed there if you need to reference. Chapter 53 detailing the messiah's life, death, and how they would not know who he was. Then immediately after that in Chapter 54 it details how the "barren woman" which is a depiction of the Gentile nations will now have part in the covenant. You see the flow there The messiah will come, then comes the age of the Gentiles, and God does this to create jealousy in people of Israel. All things work to bring people back to their creator.

Lastly, the reason I believe it was indeed the same people. Is because he was "sent to his own, and his own recieved him not." The people seen the miracles. Heard him speak. Were first hand eye witnesses, but still they turned away. Whether it was fear, or anger, or confusion doesn't matter. What matters is without them condemning him, without the blood, and cross. There would be no salvation.

I really hoped this helps you and If I'm in error I welcome any correction. God bless.

There are plenty of leafy branches (στιβάδας) out in California, which has a similar climate, during the time of the Passover. So Spong's argument, for the Palm Sunday tradition being an entirely different time such as Sukkoth, is not necessarily that compelling.

The Temple area could accommodate about 300,000 to 400,000 pilgrims. So, with Josephus giving an even larger number for those participating in the Passover, the crowd on Palm Sunday might have been only a small percentage of the total number of pilgrims being in Jerusalem for the Passover week. The 3 thousand that were baptized on the day of Pentecost, as a result of Peter's preaching, seems more credible if that crowd was composed of the same people that cheered Jesus on the Sunday before his crucifixion.