For context, one of those events started in 1945, and one in 2003. One started because we won a decisive war against the nation, in the other we invaded the co

For context, one of those events started in 1945, and one in 2003. One started because we won a decisive war against the nation, in the other we invaded the country on a flimsy excuse. We have entirely different cultures, times, mores, media landscapes, and different series of occupations, modern weaponry, 4th generation warefare (post vietnam) tactics, the list goes on. Why would "oh we didn't waste enough money occupying a country that we gained little from" be the right choice? How do we magically know that?