Not all the unsaved perish at the second coming. The entire purpose of the thousand years is to rule the unsaved nations and keep Satan from them. When Satan is freed, he goes after them again.
"Every Mans Work Will Be Tried By This Fire"
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.
"Destroyed Them All" (Fact)
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.
The Earth, World, And "ALL" That Dwell Therein (Fact)
Nahum 1:5KJV
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.