Why do Americans consider many soldiers war heroes?

Is not it an irony? Those people, do risk their lives, but for what? They go into battle and kill others, trade their lives, and that just for oil. They help imperialist purposes to steal the mineral rich from one country to another. And then if they survive they are considered war heroes. Even they, influenced by their society, thing they are going to war for they country, and definitely don't consider what they do the way described above.