Even if a collapsing America doesn’t use it, I would be very concerned about all of it ending up in the hands of whatever successor state(s) and what they might do with it. A major concern of the world with the Soviet Union collapse was the status of the nukes and making sure random warlords and terrorist groups didn’t somehow get ahold of the nukes or fissile materials from the nukes since they likely couldn’t attain the nuke and launch code