The real currency here isn't just fiat it's trust. Trust that your sacrifice means something. Trust that your family will be taken care of if something happens to you. Trust that the cause is legitimate.
it’s more patriotism more than anything else
soldiers go into military because they want to serve their country first and foremost everything else comes in second sometimes they don’t even question what they are being told to do because they trust that whatever it may be, it’s for the greater good or at least good for the country
in short, patriotism is what glues the military together and not material or financial purposes