Thats because Peter says the Day of the Lord will come as a thief then the elements dissolve and there's a new heaven and earth where only righteousness dwell. 2 Peter 3:10-13
Then Paul says something similar in about the Day of the Lord coming like a thief when there is sudden destruction. 1 Thessalonians 5:1-3
Jesus echos the same narrative. People are eating, drinking, and marrying like in the days before the flood then suddenly the flood came and washed them away. Then Jesus returns like a thief in the night. Matthew 24:36-43
Then Jesus says He comes as a thief in Revelation 16:15 so we should be expecting some sort of destructive event happening after He comes as a thief and then the destruction happens in Revelation 16:16-22.
Peter says the New Heaven and New Earth come after this destructive event with loud bangs and fervent heat in 2 Peter 3:10-13 and the event described in Revelation 16:16-22 would probably involve loud noises and heat since it involves thunder and lightning.
Now we're in track to get our prophesied New Heaven and Earth, but what comes by Revelation 20:1-6 is the 1,000 year millennial kingdom which is not mentioned anywhere else in the Bible.
Finally, the New Hevean and New Earth appear in Revelation 21:1-5 after the great white throne judgment Revelation 20:11-15.
The millennial kingdom is a bit of a curve ball, but we must factor it in because it's mentioned. So how it is factored in becomes a point of debate depending on your eschatological interpretation, but we should strive to let the Bible speak for itself under the belief it's the infallible written word of God.
The millennial kingdom is before the new heaven and earth. As noted in Revelation 16:16-22 the surface of the Earth was already leveled, the cities, and the great city fractured into three parts. The millennial kingdom happens among ruins or do they rebuild?
Then earth and heavens get made new anyway? It's possibly a parallel teaching of a previously stated concept. Does Matthew 3:23-27 ring any bells?
In conclusion, the millennial kingdom is either literal or not literal. People struggle to find a way to explain it. People usually interpret it based around their previous eschatological theology which is usually pre-trib, mid-trib, or post-trib rapture.
You Will Continue To Pose The Question, I Will Continue To Give The Answer
There is no question that the 1,000 years in Revelation 20:1-6 is (Symbolic), as stated before, all elements seen are 100% in the Lords spiritual realm of (No Literal Earthly Time) Angel, Heaven, Devil, Satan, The Souls, The Dead, God, Christ?
(Fact) No Literal Kingdom, No Mortal Humans Are Seen As Millennialist Claim, These Being A Big Fabricated Fairy Tale, Just As A Pre-Trib Rapture.
As Scripture "Clearly Teaches" The Lord Returns In Fire (Dissolving This Earth)
There Will Be No 1,000 Year Millennial Kingdom Upon This Earth, Jesus Christ Returns In Fire And Final Judgement, Dissolving This Existing Earth By Fire, Immediately After The Tribulation.
This Existing Heaven And Earth Will Be (Replaced) By The New Heaven, Earth, Jerusalem, A New Creation, At The Return Of Jesus Christ!
(Behold, I Make All Things New)
2 Peter 3:10-13KJV
10 But the day of the Lord will come as a thief in the night; in the which
the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up.
11 Seeing then that all these things shall be dissolved, what manner of persons ought ye to be in all holy conversation and godliness,
12 Looking for and hasting unto the coming of the day of God,
wherein the heavens being on fire shall be dissolved, and the elements shall melt with fervent heat?
13 Nevertheless we, according to his promise, look for new heavens and a new earth, wherein dwelleth righteousness.
Revelation 21:1-5KJV
1 And
I saw a new heaven and a new earth: for the first heaven and the first earth were passed away; and there was no more sea.
2 And I John saw the holy city, new Jerusalem, coming down from God out of heaven, prepared as a bride adorned for her husband.
3 And I heard a great voice out of heaven saying, Behold, the tabernacle of God is with men, and he will dwell with them, and they shall be his people, and God himself shall be with them, and be their God.
4 And God shall wipe away all tears from their eyes; and there shall be no more death, neither sorrow, nor crying, neither shall there be any more pain: for the former things are passed away.
5 And he that sat upon the throne said,
Behold, I make all things new. And he said unto me, Write: for these words are true and faithful.
Matthew 24:29-30KJV
29
Immediately after the tribulation of those days shall the sun be darkened, and the moon shall not give her light, and the stars shall fall from heaven, and the powers of the heavens shall be shaken:
30 And then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and
they shall see the Son of man coming in the clouds of heaven with power and great glory.
1 Corinthians 3:13KJV
13
Every man's work shall be made manifest: for the day shall declare it, because it shall be revealed by fire; and
the fire shall try every man's work of what sort it is.
Luke 17:29-30KJV
29 But the same day that Lot went out of Sodom
it rained fire and brimstone from heaven, and destroyed them all.
30 Even thus shall it be in the day when the Son of man is revealed.
2 Thessalonians 1:7-9KJV
7 And to you who are troubled rest with us, when
the Lord Jesus shall be revealed from heaven with his mighty angels,
8 In flaming fire taking vengeance on them that know not God, and that obey not the gospel of our Lord Jesus Christ:
9 Who shall be punished with everlasting destruction from the presence of the Lord, and from the glory of his power;
Malachi 3:2KJV
2
But who may abide the day of his coming? and who shall stand
when he appeareth? for
he is like a refiner's fire, and like fullers' soap:
Psalm 46:6KJV
6 The heathen raged, the kingdoms were moved: he uttered his voice,
the earth melted.
Psalm 50:3KJV
3
Our God shall come, and shall not keep silence:
a fire shall devour before him, and it shall be very tempestuous round about him.
Psalm 97:5KJV
5
The hills melted like wax at the presence of the Lord, at the presence of the Lord of the whole earth.
Isaiah 66:15KJV
15
For, behold, the Lord will come with fire, and with his chariots like a whirlwind, to render his anger with fury, and
his rebuke with flames of fire.
Zechariah 14:12KJV
12 And this shall be the plague wherewith the Lord will smite all the people that have fought against Jerusalem;
Their flesh shall consume away while they stand upon their feet, and their eyes shall consume away in their holes, and their tongue shall consume away in their mouth.
Nahum 1:5-6KJV
5 The mountains quake at him, and the hills melt, and
the earth is burned at his presence, yea, the world, and all that dwell therein.
6 Who can stand before his indignation? and who can abide in the fierceness of his anger?
his fury is poured out like fire, and the rocks are thrown down by him.
Revelation 20:9KJV
9 And they went up on the breadth of the earth, and compassed the camp of the saints about, and the beloved city: and
fire came down from God out of heaven, and devoured them.