Communism wasn’t the threat. The threat was an imperialistic/expansionistic Russian “empire” with nuclear weapons.
This threat was exxagerated by a military/industrial/congressional complex that justified its existence by that threat. It was hard to justify spending half our budget on military items unless we believed there was an existential threat and the nukes made that threat seem credible.
I’m 43, and fairly well-informed, but I had no idea what had gone on in Russia until I started reading “The Gulag Archipelago” by Alexandr Solzhenitsyn -** no idea**. I knew that the US and Russia had had bad blood for decades, but I understood nothing of why. I used to think people over-reacted to the dangers of communism; I don’t think so anymore.
ETA: I should say that I actually think Communism has some good ideas - it seems that human beings can’t implement them without losing their minds and killing everyone, though.
I remember the 50s and 60s. Keep in mind that many many people had returned from World War 2 and the memory was still fresh in their minds. They had seen first hand, what an authoritarian system could do and it wasn’t good. They were also well aware of “Uncle Joe” Stalin, who was as bad as Hitler and just as dangerous. So there was a very real fear of what was often viewed a a huge, monolithic threat. Later on, when the Soviets acquired nuclear capability, it was seemed reasonable to assume they were “meant for us”. Couple that with Soviet expansion into the “buffer” countries immediately after the war, and you can see why many people looked at “the Commies” as our enemy.
And so, “we” came up with MAD - mutually assured destruction. If you attack us, you die with us. Given the climate at the time, it’s understandable. We were afraid of them.
FORTUNATELY, no one was crazy or stupid enough to start World War 3.