This attitude is part of 'better to be dead than a slave'. I think many people saw what the Nazis did in the occupied territories and their thinking was influenced by that (extending it to, what would happen if the Soviets invaded our lands).
https://en.wikipedia.org/wiki/One_Day_in_the_Life_of_Ivan_De...
That's not to excuse or downplay these country's mistakes. Let's just not forget our own.
It was between maintaining the capability of such a nuclear war to deter aggression, and not maintaining it and surely having been invaded by the Soviets.
For the madness that MAD was, for all intents and purposes, it actually worked.
Of course, deterrence based on MAD is the least worst idea - but once shooting actually started, what is the rational thing to do?