Torah Temimah citing Megilah 15b: All his treasures were carved on his heart, and when he saw Mordechai sitting in the gate of the king, he said "all this is not worth to me."

Torah Temimah citing Megilah 15a: Mordechai came with his Pruzbul (wealth), and Haman came with his Pruzbuti (poverty). Mordechai called him 'a slave that was sold for bread.' Rashi (from Yalkut Esther - previously, Haman had no food and had to sell himself to be Mordechai's slave, when they were officers together in a war. Etz Yosef (15a) - Mordechai told him that anything a slave acquires belongs to his master.

Rashi: I am not concerned for all the honor that I have.

Malbim: All my grandeur cannot equal the disgrace I get from Mordechai. My grandeur increases his sin, but also prevents me from striking him, lest it lower my honor! Haman asked how to kill him, and it will not be disgraceful for him.