While Haman had wanted revenge on the Jews, he also wanted to profit from it. The first law that Haman got passed allowed for looting of the Jews’ property (Est 3:13), similar to the looting of Jewish property by the Nazis.
The attitude of the Jews is contrasted here. The second edict allowed them to “to plunder the property of their enemies” (Est 8:11), yet they did not. But why not? Why did they not take what was rightfully theirs legally?