Precisely, can technology exclusive to war feed the people? Can it improve living conditions? Better war tech means for a better army and more resource raids but I doubt it can go on forever. It would have been more true-to-life if we saw that a culture built on war and an economy dedicated to the military over all else left the common non-warrior Klingon living in squalor.
Funnily enough, yes. Advances in military technology are usually accompanied by leaps in the quality of civilian life, simply because military technology really does trickle down the the civilian sector with rather powerful results. Everything from computers to jet aircraft to nuclear power were gleaned from military advances. Many engineering techniques that are now common were pioneered by military engineers. The amount of stuff that we take for granted which was derived from military technology is staggering.