Esther’s life was overall a very tragic one. The story ends, and we’re told about Mordechai’s rise to political power and the taxes and all. Meanwhile, she is still married to a non-Jewish drunkard who killed a previous wife on a whim. No happily ever after for her!
And I think this is what Esther was thinking of when she said
לֵךְ֩ כְּנ֨וֹס אֶת־כָּל־הַיְּהוּדִ֜ים הַֽנִּמְצְאִ֣ים בְּשׁוּשָׁ֗ן וְצ֣וּמוּ עָ֠לַי וְאַל־תֹּאכְל֨וּ וְאַל־תִּשְׁתּ֜וּ שְׁלֹ֤שֶׁת יָמִים֙ לַ֣יְלָה וָי֔וֹם גַּם־אֲנִ֥י וְנַעֲרֹתַ֖י אָצ֣וּם כֵּ֑ן וּבְכֵ֞ן אָב֤וֹא אֶל־הַמֶּ֙לֶךְ֙ אֲשֶׁ֣ר לֹֽא־כַדָּ֔ת וְכַאֲשֶׁ֥ר אָבַ֖דְתִּי אָבָֽדְתִּי׃
Go, gather all the Jews who can be found in Shushan, and fast for me; do not eat nor drink for three days — night and day — and I and my maids will similarly fast; with that, I will come before the kiing in a manner against the law —
and however I am lost, I am lost.
Esther realized that her life was lost either way. As Rashi (ad loc) puts it, “וכאשר התחלתי לילך לאבוד אלך ואמות — just as I started to be lost, I can [equally] go to death.” But rather than despairing of everything, she used it as motivation to shift her life from a pursuit of happiness to a pursuit of meaning. Since I am lost either way, let me see what I can do to save the Jewish people.
Esther brings this attitude forward through the rest of her life. Rashi (on Ezra 4:24) portrays her after the story of Purim, after the death of Achashveirosh, as an active Queen Mother, still meddling, this time with her son, Daryavesh (Darius), on behalf of the Jewish people. It is from Esther’s prodding that Daryavesh agrees to let us begin to build the second Beis haMiqdash.
In contrast, we have Haman. Haman had everything. Private parties with the royal couple. Power second to the king himself. There was even a law requiring everyone to bow to him! He had everything, that is, except one local dignitary from a small ethnic group, who refused to bow.
וְכָל־זֶ֕ה אֵינֶ֥נּוּ שֹׁוֶ֖ה לִ֑י בְּכָל־עֵ֗ת אֲשֶׁ֨ר אֲנִ֤י רֹאֶה֙ אֶת־מָרְדֳּכַ֣י הַיְּהוּדִ֔י יוֹשֵׁ֖ב בְּשַׁ֥עַר הַמֶּֽלֶךְ׃
And all this is worthless to me whenever I see Mordachai the Jew sitting in the king’s gate.
Haman has little reason to be sad, but he can’t see past the one flaw in his otherwise perfect picture. Eeyore style, he can only see life’s problems. Esther commits to fixing the problems, and therefore gets a measure of value and contentment out of a life that appears destined for personal misery. More inheres in what each chose to look for in life, than what life actually gave them.