Their gods forsake them.

Rev. 18:9-18 (ESV)
And the kings of the earth, who committed sexual immorality and lived in luxury with her, will weep and wail over her when they see the smoke of her burning. [10] They will stand far off, in fear of her torment, and say,

"Alas! Alas! You great city,
you mighty city, Babylon!
For in a single hour your judgment has come."

[11] And the merchants of the earth weep and mourn for her, since no one buys their cargo anymore, [12] cargo of gold, silver, jewels, pearls, fine linen, purple cloth, silk, scarlet cloth, all kinds of scented wood, all kinds of articles of ivory, all kinds of articles of costly wood, bronze, iron and marble, [13] cinnamon, spice, incense, myrrh, frankincense, wine, oil, fine flour, wheat, cattle and sheep, horses and chariots, and slaves, that is, human souls.

[14] "The fruit for which your soul longed
has gone from you,
and all your delicacies and your splendors
are lost to you,
never to be found again!"
[15] The merchants of these wares, who gained wealth from her, will stand far off, in fear of her torment, weeping and mourning aloud,

[16] "Alas, alas, for the great city
that was clothed in fine linen,
in purple and scarlet,
adorned with gold,
with jewels, and with pearls!
[17] For in a single hour all this wealth has been laid waste."

And all shipmasters and seafaring men, sailors and all whose trade is on the sea, stood far off [18] and cried out as they saw the smoke of her burning,

"What city was like the great city?"
and cried out as they saw the smoke of her burning,
"What city was like the great city?"
[19] And they threw dust on their heads as they wept and mourned, crying out,
"Alas, alas, for the great city
where all who had ships at sea
grew rich by her wealth!
For in a single hour she has been laid waste. “

Political Rulers, merchants, and Sailors all morn the destruction of the city, the great Babylon. Government is necessary for trade, and trade is necessary for luxury. These men morn the fall because they have been cut off from the luxury they have grown accustomed too. The things of this world became their God, those things that they loved even more than God. So they morn, for in a single hour the city is laid waste. In a single hour their fortunes are ruined, and they have nothing left. Their gods have forsaken them.