Why does the US want to pay trillions for regime changes?

Beware. Not long ago your statement would be considered terrorist. USA became the Great Uncle of the world. Let's put it in other words: if those dictators are a real nuisance, why just not shoot them? It was easy in the case of Lincoln, Kennedy (both) or Martin Luther. Not to mention the shootings that failed, like Reagan and Ford. There is much more behind politics, my friend. For instance, my country, which HATES communism, will support some regimes like Castro and Ahmennajad. Why? Because someone should balance the world politics. And we got the dirty job.