The problem is that asymmetric warfare, which is the best way to win a war, is the worst way to acquire capital.

The best way to win a war is to have an overwhelming advantage. That sort is situation is much better described by the word "lopsided". Asymmetric warfare is something different.

Example: Iraqi invasion of Kuwait.

Spying, subversion, and purchasing are far cheaper, safer, and more effective means of capturing capital than violence.

Spying can capture technology, but technology is not the same thing as capital. Neither subversion nor purchasing are "means of capturing capital" at all. Subversion destroys capital and purchases are exchanges of assets.

As far as "never" goes - the last time any two "Western" countries were at war was World War II, which was more or less when the "West" came to be in the first place.

That's an unusual idea of the West. It looks to me like it was custom-made to fit your thesis.

Can you provide a definition? One sufficiently precise to be able to allocate countries like Poland, Israel, Chile, British Virgin Islands, Estonia, etc. to either "West" or "not-West".