For me, the more important caution is that military spending is a massive amount of private purchasing for something we ultimately don't want to happen. Private purchasing by the state begets private purchasing by the state, it creates an enemy of the people and worsens the system of governance. Those companies want not to provide means of defense but to make money. The only way to consistently make more money, or maybe the easiest, when your wares are only purchasable by the state is to encourage the state to buy more.

This is a systemic method for warping any countries budget, like the USA, and encouraging war - not preventing it. The more you spend on defense the more your country will use it and the worse it'll be for the world when they decide to.

It's simultaneously removing money from the places that benefit people the most, creating a systemic enemy of the people, and building a pathway to future wars. Prevention could just as easily be guaranteed with economic and cultural infrastructure/exchange/ties.