I doubt there's very many libertarians that would claim the private sector doesn't benefit from government spending at times. Every complex issue has it's nuances.
Generally, the stance of libertarians is that the TCO associated with the military industrial complex FAR outweigh it's benefit.
"At times" grossly understates the role of DARPA and other government support in creating technologies commercialized by Silicon Valley. The entire industry was a direct product of public investment and most key innovations are a culmination of long-term sustained taxpayer-funded research.
And there are drones killing civilians in the middle east. Though we benefit greatly in the private sector from this relationship, some of us consider the harm it creates much greater.
I had a very interesting talk with Vint Cerf about this a while back btw. It's a sad situation to be in.
I'm not sure. We had a good conversation of the good and bad of working with groups like the DOD. He's happy to be with Google and recognizes the benefit of working with the DOD, but not exactly pro military.
Generally, the stance of libertarians is that the TCO associated with the military industrial complex FAR outweigh it's benefit.