You have to spend enough to protect yourself against any coalition of adversaries who may stand against you. Your adversaries in turn need to be able to spend enough to ward off any attack that you and some of your allies threaten them with which means they have to spend more meaning well now you need to increase your budget because all of your adversaries just increased their budgets and so on und so weiter until you just sort of say gosh I don’t know this game seems kind of silly