“The results found that 100 nuclear warheads are adequate for nuclear deterrence in the worst case scenario, while using more than 100 nuclear weapons by any aggressor nation (including the best positioned strategically to handle the unintended consequences) even with optimistic assumptions (including no retaliation) would cause unacceptable damage to their own society.” – source

You had the same reaction I did. Seems like once you have enough nuclear weapons to destroy humanity, you have more than enough.