Military spending is an easy trap for a developed country to fall into. Once all basic needs are met, there isn't much to do. A stockpile of weapons might not be useful immediately, but it is a better "investment" than doing nothing.

The problem with weapon stockpiles though (I include well educated personnel that can use those weapons as part of the stockpile), is that it is inherently negative sum. A neighboring country may feel threatened and thus increase their stockpile. Then one accident or harmless aggression occurs and the calculation shifts in favor of "deploying" those weapons, leading to a far bigger war than is actually necessary to settle the original dispute.