The economics are easy. Money on war 'invests' your resources into other countries (no return, negative return likely), vs. money on innovation and infrastructure in your own country (positive return, long-term; potential for making other things more efficient, more cost-efficient become higher).
Sorry, but that's nonsense, you cannot underestimate the impact of military technologies like jet engines, radar, communications satellites, GPS, the internet, superglue... The whole of the modern world is based on military tech. Plus you gainfully employ lots of people (e.g. teaching trades to people who haven't done well in mainstream education) and as a free bonus you get the defence of the realm.
You are comparing the benefits of war to the wrong base. The civilians wouldn't have just burned all the riches (like war literally does to some extent), but would have used it to develop new products, too.
Nowadays the military actually uses consumer electronics.
You need to separate contexts of war and innovation. An example, this innovation could come through a budget for space exploration, or other means of transportation. The world is based on science tech. Yes, a lot was discovered in science through military budgets, but it's not exclusive to being put into the military - which I think can easily be argued has huge wastes of resources just by looking at industrial complex structures.
>jet engines, radar, communications satellites, GPS, the internet, superglue
Don't forget computers: Turing's work relies heavily on his experiences working at Bletchley Park, ENIAC was designed to calculate artillery firing tables for the United States Army's Ballistic Research Laboratory, and the calculational needs of the Manhattan Project drove a lot of early computer development.
Yes, but Konrad Zuse was driven to do his early computers by the tedium of doing arithmetic by hand in his engineering bureau. So we would have gotten computers anyway.
Yes and no. It is true that Zuse's early work, starting in 1936, was done on his own and (I will grant) motivated by non-military calculations. But that early work was on a purely mechanical computer, like the analytical engine and the difference engine of Charles Babbage -- and no mechanical designs were ever realized (except much later as part of the "retrocomputing" movement when their computing capabilities were no longer needed). By the time Zuse started incorporating electrical relays into his designs, in 1939, he was a member of the German military. It looks like he might have left the German military before the end of the Nazi era, but that matters little because the whole of German society was organized around military needs and military goals.
More importantly, the argument that "we would have gotten X anyways" can be applied to almost any technological development. Speed of development is important, however, even if all you care about is whether humans reach a certain level of development eventually (because the longer it takes to reach that level, the greater the chance that one of many potential catastrophes causes humans to die out or to lose the ability to invent the radically new technologies).
