Does military spending have the same problem as buying computer hardware?

[Smith_3]

Consider you want a top of the line PC. You can spend 3000$ and get one that is bad ass. Three years from now though, people will be buying the same stuff for a fraction of the cash. In order to always stay at cutting edge, you have to spend over-proportional amounts of cash.

I wonder wether it works the same for the military. Can it be, that wrecking your own economy and social system for a superior military technology is ultimately not sustainable? Can it be, that all new the stuff we get by investing huge parts of our gross domestic product into, will always easily be available to foreign powers for a cheap price, five years later?

Is it really worth blowing so much money to maintain such a small edge?