Possibly their leaders retained some small degree of rationality and/or empathy even at the most stressful moments (however I doubt that either the current United States president or Russian Federation president are capable of either rationality or empathy).
Possibly it was entirely sheer blind luck.
Possibly (if you are religious) God decided not to let them do it.
Possibly we will never know.
Chat with our AI personalities
Because there was no true defense against nuclear weapons. Once both sides had nuclear weapons, the only way to "protect" themselves from the other side was to have so many more nuclear weapons that even if their enemies used all of their nuclear weapons, there would still be nuclear weapons to shoot back with. That way, nobody would use nuclear weapons, because they could never actually "win" that way. This thought process was referred to as Mutually Assured Destruction, or MAD.
No, Cuba never had control of a large amount of nuclear weapons, the Soviet Union placed them their in reaction to the US placing Nuclear weapons on West Germany, Greece, Turkey, and some pacific island. The US threatened a huge invasion or nuclear strike against Cuba after they discovered the Nuclear weapons in Cuba
The first Soviet nuclear weapon was tested in 1949. They have never used one in combat.
In war, never.
It was born on 06 August 1945, and escalated from there. There NEVER was a nuclear war. It matured with newer, faster, deadlier, bigger nuclear weapons that were NEVER used.