The answer seems to me to lie in the association that the Bible makes with bad kings and beasts. When a person fails to rule over himself and gives into sin, and participates in false worship, he becomes beastly. When a king fails to rule righteously and show mercy to the oppressed, and when he participates in false worship, he becomes a beastly king.
Failure to Worship Leads to Beastliness and to Being Cast Out
First, Adam falls by worshiping a beast, by serving the creature rather than the Creator. The Tree of Knowledge was a kingly tree that would have advanced him to righteous kingship if he had exercised patient faith. He is still given rule but he is a beastly king and is then clothed in beast-skins. You become what you worship. Worship beasts and you become beastly and you are cast out from God’s presence. Adam was cast from the Garden.
Next Cain is told to rule over himself and his sinfulness. He is told this using beast-like language.
‘The LORD said to Cain, “Why are you angry, and why has your face fallen? If you do well, will you not be accepted? And if you do not do well, sin is crouching at the door. Its desire is for you, but you must rule over it.”’
Sin is crouching like a beast ready to attack and rule Cain but Cain must rule over sin by worshiping the Creator properly. Cain fails to rule, he fails to worship rightly, and behaves beast-like in killing his brother and is given a mark. The original mark of a beast. Cain is cast out from the Land of Eden.
Solomon breaks the three laws of kingship (Deut 17:14-20;1Kings 10-11; ). Solomon falls, apostatizes into false worship, and becomes a beast-king. He then oppresses the people (1Kings 12:4;). The book of Revelation uses Solomon as an example of a bad beastly king. One of the three laws that Solomon breaks is the multiplying of silver and gold to himself. He collects 666 talents of gold each year. The number of the beast-king that exercises authority wickedly in Revelation chapter 13 is the number 666. The number of an apostate beastly king. This Revelation beast-king is also associated with giving a mark on those who will worship improperly, which draws from the story of Cain. While Solomon is not cast out, his son’s rule suffers a kind of casting out or separation from 10 of the tribes.
Nebuchadnezzar repeatedly behaves like a beastly king in Daniel 1-3. In chapter 1, he places in them in a compromising, life threatening situation. He directly threatens the lives of Daniel and his three friends in chapter 2. He sets up false worship and throws Daniel’s three friends into the fire in chapter 3. I think that this setting up of false worship completes the beast-king pattern in Nebuchadnezzar’s life. Daniel warns him to repent and to rule with righteousness.
But Nebuchadnezzar indulges in self worship in chapter 4:30 (probably was doing that in chapter 3 with the golden image connecting to the golden head of chapter 2). He is worshiping the creature rather than the Creator. Even though he knows Yahweh, he did not honor Yahweh or give thanks to Him. So his foolish heart is darkened and Yahweh gives Nebuchadnezzar over to his own beastliness. Nebuchadnezzar is cast out for 7 periods of time.