How did being part of NATO help/hurt the US in the cold war?

Answer 1

Nato helped defend against the forced spread on Russian style Communism. After the end of WW2 there was in place a promise on all sides that the Eastern States, Bulgaria, Romania, etc, would be allowed to have free elections. Some did, but the occupying Soviets saw to it that those nations became communist. NATO gave the US and the other free countries a line where the Soviets could cross only at their peril. It stopped Greece from becoming communist and Turkey as well.
With the help of NATO we were allowed to have bases to face down the Soviets. We would still fight them in Korea and Vietnam, but only a war in Europe would have led to WW3.
NATO took some weight off the US shoulders and let us oppose Communism in other locations. It was not perfect, but I think the results speak for themselves.

Answer 2

~Until our Nazis, Werner Von Braun and his buddies from Operation Paperclip, learned to build an ICBM that could hit China and the USSR from Kansas, NATO gave us bases from which we could launch smaller missiles. When we put them in Turkey, the Soviets responded by putting them in Cuba. But for the wisdom of Nikita Khrushchev in blinking so JFK would back down, that little episode could easily have incinerated the entire world. It's up to you to decide if that helped or hurt.