"Resources"? At the end of the day, a soldier needs you to put food in him -- just like anyone else. That food comes from somewhere. It is scarce. It is not free. This is aside from all the things he'll expect to be able to buy with his pay that use resources, or the uniform / weapons / boats / fuel / et cetera.
While an army is a useful insurance policy in a variety of situations, the best case scenario is really that these people do nothing. Believe it or not, it does not make the Greek people any more prosperous to have many people standing around doing nothing, unless the money you pay them to do it comes from somewhere other than Greece and isn't ever going to be paid back.
-- which, to be fair, is a tactic that works once every few generations! One could make a case that it is a simplified version the story of Greece the past decade. You see these debt renegotiation promises in the news now.
More broadly, though, the economy is about producing valuable things (or services), not about money. It is trivially obvious that an idle soldier is not producing much of value at his post and cannot assist the economy in any way. Even middle-management at IBM at least pretends that they're helping accomplish something worth money to someone.
And nowhere in the history of the world has ever been able to fix economic stagnation or crisis by spending more money on the military, though it has run great empires into the ground.