The 80 years thing actually happened. One can argue about MAD and the nuclear threat, but we don't have to guess at what happened.
It worked.
It worked.
If Stanislav Petrov hadn't been in the chain of command, MAD might not have worked. And it could still fail to work in the future.
https://en.wikipedia.org/wiki/1983_Soviet_nuclear_false_alar... https://en.wikipedia.org/wiki/Stanislav_Petrov