Is it though? US growth during WW2 was enabled by physical destruction of most competition. The Cold War enabled technological advancement which wouldn't have happened otherwise (just look at space investment pre and post '92).
Conflicts hold growth down only when you don't win them.
> (just look at space investment pre and post '92)
For some context for anyone curious about this, my summary of the tables at https://en.wikipedia.org/wiki/Budget_of_NASA is the following: It appears that the average annual budget of NASA in both of the periods 1960--1992 and 1992--present is just under $20 billion present-USD per year (ie after adjusting for inflation).
The time series behavior is that NASA's budget peaked in the 1960s for the Apollo program at over $40 billion present-USD/year (and so over 4% of the federal budget at the time), then was relatively smaller during the 1970s and 1980s, and finally slightly larger and relatively flat since 1990. Beginning in 1971, the annual budget may be summarized as within 25% of the aforementioned ~$19 billion present-USD/year, noting that the wide range primarily hides growth since then, rather than a decrease.
(I have not looked into space investment other than NASA.)
Global GDP had a huge hit during the war, and after peace was achieved growth accelerated tremendously worldwide. The economic growth of both the US and Europe after the war was clearly thanks to peace, not thanks to the spoils of war.
Conflicts hold growth down only when you don't win them.