Vilna Gaon: Achashverosh gave Yisrael to Haman as a sale - "ha'Kesef Nasun Lach" (3:11), i.e. [I return the money] for a gift. He did not say '[the money] is pardoned.' I give to you money, as if I received it, and afterwards gave [it back] to Haman.

Malbim: She has two claims. (a) The sale was primarily for her. Haman's primary intent was to kill her via finding a pretext against her nation ¹ , and afterwards also she will be killed. Therefore, she said "Nimkarnu Ani v'Ami." (b) They were not sold for slaves, rather, to be destroyed. Her request for herself is due to grace; her request for her nation is due to good of the king. It is not glory for him to destroy an entire nation without sin!

Vilna Gaon: Corresponding to "if I found grace in your eyes", have mercy on me, for me and my nation were sold. Corresponding to "if it is good for the king", she said "had we been sold for slaves" [the king would benefit].

Malbim: Haman tricked him in two ways. (a) He said "Am Echad" - he should have specified that it is my nation! (b) The king thought that "Le'abedam" is to change their form and creed, and not to kill them. Had he deceived you only about the first (not to reveal which nation), and sold us for slaves, I would be silent and not reveal it, since the king already agreed b'Shogeg. However, the entire matter was deceit. The deceiver must be punished.

Torah Temimah citing Megilah 16a: He envied Vashti and killed her (via his counsel). He envies me, and wants to kill me!

Rashi: If he desired your benefit, he would have said to sell them for slaves and receive money for them, or to keep them, that they and their seed will be your slaves.

Vilna Gaon: He is not concerned for damage that he does to the king.

Malbim: Haman said "it is not worth leaving them" (3:8); they damage the king. Just the contrary, the afflicter is not worth leaving him alive due to the damage the king gets from him. He destroys the kingdom!