I wish to come at this topic from the side on. You must draw your own parallels and inferences.
On Industrial Foundations
High tech only happens if there are enough people to buy it. The expenses of developing and deploying any sufficiently advanced technology can only be amortised if there are enough people around who can afford to indulge in it. Not enough population, and the technology remains too expensive per unit to feasibly support a market that will pay for that tech.
Cellular telephony. If there were only (say) 10-million people in the world who could afford cellphones, then no cellphones would exist. Not a single one.
It’s not that you couldn’t produce the handheld units themselves at a reasonable price for a population of 10-million — you might well be able to figure a way to pull that off — but it would be infeasibly expensive to build all the necessary supporting infrastructure: all those cellular towers with their antennae and radios, the routers, the cables and microwave links: the backbone network and computers that make those little handheld wireless devices usable. Useful. If only rich people could afford cellphones, nobody could afford cellphones because they wouldn’t exist. The only way for rich people to have cellphones is if middle-class and even poor people can also have cellphones. The only way to make the whole network affordable at any price is to make it available to as many people as possible at a sufficiently low price. So you need a sufficiency of buying power in the market for the tech to be even minimally useable.
If a sovereign wants to go to war, they need to start preparations many years in advance. They need to procure sufficient weapons, munitions, vehicles and fuels, they need to prepare the logistic supply chains that will support their soldiers in the field, they need time to train a hierarchy of command sufficiently well versed in the arts of war for when the time comes to engage the enemy in battle. These things do not happen overnight. Now this would be all very well if, when a sovereign decides to war, they could simply begin to make appropriate preparations, procure the necessary materiel, but it is impossible: it takes years, decades to build the necessary industries to produce the requisites of war, and those industries need feeding from the get-go. They require funding on an immediate and on-going basis. If you want to know whether an enemy plans to war on you, watch the industries that supply and support war, the industries that build ships, tanks, trucks, planes, guns, missiles, bombs. Watch the industries that supply the chemicals and fuels needed to make all that hardware work, that feed, clothe, house and train the soldiers. And when the sovereign is not actively at war, but contemplates the possibility that they may have enemies who consider war, then they feel compelled to maintain their own appropriate level of preparedness for war. But.
The general who wins a battle makes many calculations in his temple before the battle is fought. The general who loses a battle makes but few calculations beforehand.
Where there are in the field a thousand swift chariots, ten thousand heavy chariots, and a hundred thousand mail-clad soldiers, with provisions enough to carry the a thousand li the expenditure at home and at the front, […] will reach the total of a thousand ounces of silver per day. Such is the cost of raising an army of a hundred thousand man.
No sovereign can, without end, sustain the expense, the drain on the treasury induced by those preparations.
The solution is to turn those precursor industries into export products. The answer is to sell warmaking to other sovereigns. The answer is to foment war between other sovereigns without involving your own forces, without depleting your own reserves, and without threat to your own sovereignty.
Thus war — particularly the stoking of foreign brush wars — becomes a necessity for the sovereign who would maintain military superiority and a high level capacity for making war. It becomes vital to ensure that other, lesser, non-threatening actors become deliberately embroiled in wars not of their own provocation, simply as a way to support your own warmaking industries and supply chains.
Peace is most decidedly not their profession.