First, we did it because it was in our national interest. It was part of our containment strategy of Communist expansion. We didn't rebuild China (PRC). We didn't rebuild East Germany or Eastern Europe.
And during these times, the US was the unquestioned world leading economic power. We were untouched by the devastation of WWII. The Marshall Plan and the Truman Doctrine gave us a world view and strategy. And we occupied Japan and West Germany giving us the needed control. We helped draft the Japanese constitution including Article 9. There was unconditional surrender.
We don't have the money to invest in nation building. And the growing welfare state will further limit our ability to project power globally. We are now experiencing the classic Guns vs Butter battle and butter always wins because it has more constituents. The sane thing happened to the UK.
Oh heck, I must be tired, I forgot Clinton’s Nato led air war....caused more problems then it fixed. and Reagans two short term interventions with no occupation. Both of those succeeded. We fixed the problems with the little island and the American school and we got Noriega. Great successes done right with a full deck of military power.
There was one more.......hmmmmm....That crap island nation in the med. Starving blacks after a storm. Happened years ago and it’s still just as bad as it was. But at least we dumped it on the international community. The UN has it now...lol