Thinking economically is the basic foundation of strategy.

My thoughts are.

LancelotDuLac...Hmmmmmmm?

Thinking is an internal electro-chemical process, whereby we assess data and sometimes apply as external actions if we deem appropriate.

Which isn't to say that appropriately deeming external actions will always be appropriate in the long run...Because events are such that, once deemed and appropriated there is no going back...It's a time thing.

Economically, is making the best of what is available.

For sure, war and fighting are still sometimes deemed appropriate...So one might argue that such events are either appropriate or uneconomical...Though such arguments usually occur after the event, and are therefore a tad futile.

Economy, resources, and cost to effect ratio are basis of everything. think about human rights. Would it be possible to feed all children if suddenly 10 billion more children appeared? Everything is cost to effect, even morality which must be economically possible in order to be applied.

The statement "there is a cost price to everything" is true, as every choice involves a trade-off. This "cost" can be a monetary price, but it also includes intangible factors like time, effort, opportunity, and emotional energy

. In economics, this is known as opportunity cost, which is the benefit you give up by choosing one option over another. For example, the cost of buying a coffee isn't just the money spent, but also the other things you could have done with that money, like saving it or buying something else. 

There are parallels between economics and game theory, one isn't the other but there are parallels absolutely yes.

Every kingdom has a currency, a form of wealth that they generate and value to trade with others to gain their wealth.

All you have to do to overcome any kingdom is stop their ability to generate currency, then make them dependent on yours, or destroy them and take what they have.

Even satan is made powerless when you refuse his currency. All he can do is destroy what is under his dominion.

You can't kill your enemy and take their stuff in peace. Maybe.

I suppose it depends a bit on who one is at war 'with.

China and Japan, I'd imagine peace often meant you either absorbed your enemy or they became your ally,

You then fought together against some other enemy.

There's an expectation of a peaceful coexistence or service.

But if you 'don't have that. . .

Then what you 'want is conflict, is war, is battle, and killing.

An excuse to take their territory.

To raze their structures to the ground and build your own.

To have their tribute.

Rome and Carthage,

Peace didn't seem to be in the cards, though I think it 'could have been if people had chosen it.

. . . I've heard that the Romans were surprised when Hannibal managed to pay of the exorbitant price the Romans had forced upon Carthage, after Rome won.

Sparta and the Helots,

The Spartans found the Helots ideal training material for war, maybe.

Perhaps also saw it as good practice to thin the herd in war.

Yes, constant wars were a major contributing factor to the weakening and eventual fall of the Western Roman Empire

. Both external invasions and frequent internal civil wars drained the empire's resources, strained its economy, and created political instability.