The reason given is that the conqueror has plundered many nations, and the remnant of the peoples will plunder him. The passage links this reversal to bloodshed and violence done to lands, cities, and their inhabitants. This is stated in Habakkuk 2:8.
Habakkuk 2:8 states a reversal: the one who has plundered many nations will be plundered in return. The verse gives reasons for this turnabout, pointing to spilled human blood and broad violence. The harm is described as reaching beyond battles to what was done to the land, to cities, and to everyone living in them. This verse sits inside the taunt-song of “woe” statements aimed at the rising imperial power accused of greedy conquest (Habakkuk 2:6–20).
Habakkuk 2:8 presents a moral reversal: an oppressor who “plundered many nations” will in turn be plundered by “all the remnant of the peoples” (Habakkuk 2:8). This is not described as random political bad luck. The verse explicitly ties the reversal to bloodshed and broad violence. The harm is portrayed as wide in scope.
A careful answer keeps the immediate passage, the book's argument, and the whole-Bible storyline together, so the question is answered in context instead of as a detached idea.
Start with Habakkuk 2:8, then read the surrounding section so the answer stays connected to the passage's flow.
8Because you have plundered many nations, all the remnant of the peoples will plunder you, because of men`s blood, and for the violence done to the land, to the city and to all who dwell in it.