How do you figure that? This is literally telling some of the people who would be growing the economy to stop doing that and focus on making military goods instead. That can't be done and also have a stronger economy. The resources for the army have to come from somewhere - they're resources being directed away from strengthening the economy towards strengthening the army.

I suppose there could be some sort of plowshares-to-swords program where they build tractors and bulldozers that can be repurposed into military gear on short notice. But I havn't heard of that working anywhere before and my read of modern militarys is that the gear gets pretty specialised to military use. And the soldiers need to actually focus on soldiering rather than being part timers.

At some level a country needs an army because without one they don't get to have an economy, but it is a dead weight in terms of prosperity. Military expenditure comes directly out of what people would otherwise use to improve their own lifestyles.