Smedley Butler said this quote

I served in all commissioned ranks from a second Lieutenant to a Major General. And during that time, I spent most of my time being a high-class muscle man for Big Business, for Wall Street, and for the bankers. In short, I was a racketeer for capitalism.

~ Smedley Butler

War is a racket. It always has been... A few profit - and the many pay. But there is a way to stop it. You can't end it by disarmament conferences. You can't eliminate it by peace parleys at Geneva. Well-meaning but impractical groups can't wipe it out by resolutions. It can be smashed effectively only by taking the profit out of war.

~ Smedley Butler

War is just a racket. A racket is best described, I believe, as something that is not what it seems to the majority of people. Only a small inside group knows what it is about. It is conducted for the benefit of the very few at the expense of the masses.

~ Smedley Butler

For a great many years, as a soldier, I had a suspicion that war was a racket; not until I retired to civil life did I fully realize it.

~ Smedley Butler