Ender was a hero to the people because he was able to not only destroy the "Buggers" but he also destroyed their home planet. Ender had saved the world and the people loved him and worshiped him as a hero, but they also were afraid of him and he was unable to return to earth. After the final battle Card writes:
"Men in uniform were hugging eachother, laughing shouting; others were weeping; some knelt or lay prostrate, and Ender knew they were caught up in prayer."
"Colonel Graff detached himself from the others and came to Ender. Tears streamed down his face, buth he was smiling. He bet over, reached out his arms, and to Ender's surprise he embraced him held him tightly, and whispered, "Thank you, Thank you Ender. Thank God for you Ender." (pg 255)