If you read the story of the Megillah you will see that around the time of the original Purim Jews were living safely and securely and having a good life. The king said to bow down to his minister Haman and everyone followed.
Only one Jew refused to follow orders! This incensed the King’s minister and he decided to put the entire Jewish people to death.
Why did Mordechai have to rock the boat?!! Just bow! Big deal, move on.
Mordechai is a giant because he reminds us that by bowing you sacrifice your dignity and your basic Jewish values and you have nothing left as a Jewish People. You soon disintegrate and assimilate and you are lost.
It is because of Mordechai that me and you are here to celebrate another Purim!
Mendel (Menachem) Bluming