Rational? The CIA estimates global military expenditures in 2007 as 1,200,000,000,000 dollars. The Stockholm Institute for Peace Research says 1,158,000,000,000. That is only the strict expenditure, bnot counting the loss of productive labour to humanity from employing people in the military or the costs caused by armed conflict. The RC claims 2,255,000 active troops, the USA has 1,426,000, India about the same number, Russia 1,200,000, North Korea about 1,100,000, and 40 more countries number over 100,000 active troops. This is not counting paramilitary forces or civilians employed in the arms industry or military support. Even if you assume that humanity has no other pressing needs, I'd much rather have had a manned Mars mission for that kind of cash.
Bright day
And imagine if all taxes were abolished and all the goverment clerks were free to better their work through a honest work!
Those people are not lost, nor is the money. Without goverment investment this kind of capital would for most part not accumulate.