...Massive government spending is required to fund war and bitcoin couldn't facilitate that.
If bitcoin were to ever be a core currency, why wouldn't governments use it like they used Gold for centuries? Issue your own notes backed by bitcoin, offer a redemption option to generate confidence, but print up to 10 times more in notes than you have in bitcoin reserve, and hope there's no run. That *does* work for a while, and can certainly work to finance wars. Eventually it fails, but memories are short...each generation of politicians seems to have to learn the same lessons for themselves via first-hand experience.