The Marshall Plan was as pragmatic as it was altruistic. The alternative, letting the defeated countries struggle to rebuild on their own, was what started WWII in Europe in the first place. I don't feel qualified to make claims about which was foremost on the minds of the Truman administration, but I'm certain that the practicalities were given some thought. As far as intervention in Korea and Vietnam is concerned, the primary aim of the U.S. was to prevent the spread of Communism, not to aid the populace. We sponsored as many rebels as the Soviets did, and with no more consideration of their moral standing.