It requires a simple comprehension of world events & history to be able to understand why we used it. Obviously you don't have that.

In the simplest terms, it was to halt the atrocities committed by the Japanese & the Germans, and to end WWII. Somehow they just wouldn't take that bouquet of flowers, and stop the forced cannibalization of American POW's, and Hitler didn't free the people after we gave him a fluffy kitten.

By the way, the world disagrees with you.