It is true Carter was inept at foreign policy because he lacked the foresite as to how this would impact the country in the future. Ragan was not that great either he was only able to tack advantage of the fact that communist countries where already falling due to failed economies. It is only when government can't afford wars that the are able to be overthrown easily.
I'm sure Jimmy Carter didn't help, he was a very weak leader but these countries fell on their own. The USA is not the world's babysitter..we cannot and should not fight all the battles. For many of these countries they have had issues for decades If not centuries.