War is profitable in capitalism, because the dogma is that capital is productive and must net a positive return.
In the underutilized capital scenario, idle capital incurs costs, but no benefits. It must be destroyed. The easiest way to maintain the facade is to send the capital to war. If you acquire new land, congratulations, the "investment" paid off. If it doesn't, then the destruction of capital at least maintains the profitability of domestic capital.
War is really that simple. If you had a war for any other reason, everyone involved would see the stupidity after the first few skirmishes.
War has existed since the dawn of humanity, thousands of years prior to the advent of capitalism, and has been fought by societies with every kind of socioeconomic and political configuration. War is a human institution and not contingent upon a particular economic arrangement.
I do believe that people from the USA are extremely more likely to view war as profitable and not a huge money sinc.
And I have to wonder is there a connection to WW2, where USA exported about $32.5 billion worth of goods through Lend-Lease, indebting a number of nations in the process, while having almost zero repair damage (yes, Perl Harbor, of course a tragedy, but it was a small town, and Europe had cities that were bombed for years, and that had to be rebuild almost from scratch)
The process of repairing Europe costed a lot. Not to mention paying back the land-lease!
So yeah huge money sink for everyone who are on a continent the war is on. And profitable for leasers because everyone actively at war is kinda forced to take the deal.
In the underutilized capital scenario, idle capital incurs costs, but no benefits. It must be destroyed. The easiest way to maintain the facade is to send the capital to war. If you acquire new land, congratulations, the "investment" paid off. If it doesn't, then the destruction of capital at least maintains the profitability of domestic capital.
War is really that simple. If you had a war for any other reason, everyone involved would see the stupidity after the first few skirmishes.