What do you gain from having additional warheads? If you have enough to kill all enemy decision makers and effectively destroy the enemy nation then having mor

What do you gain from having additional warheads? If you have enough to kill all enemy decision makers and effectively destroy the enemy nation then having more doesn't do anything for you. The big cost is that your enemy will discover you are secretly amassing nuclear weapons and will escalate against you. Incentives seem to align to keeping relatively low numbers of nukes to me.