About your first point, MAD was actually developed by John von Neumann and there is nothing accidental about it.
'He also "moved heaven and earth" to bring MAD about.' https://en.wikipedia.org/wiki/John_von_Neumann#Mutual_assure...
> [The Soviets] believed that whoever had superiority in these weapons would take over the world, without necessarily using them. He was afraid of a "missile gap" and took several more steps to achieve his goal of keeping up with the Soviets
(This is an except from the parent's wikipedia link)