Re: A rounding error in the defense budget
I wish I could be as optimistic as you appear to be, but I've been around long enough to know that "lessons learned" are quite often "lessons forgotten."
You have only to read the puff piece in the Atlantic on General Milley to realize how quickly we forget.
Amidst all the Trump and glory, this passage on Milley's formative years is about all you need to know: "This was during the Reagan-era defense buildup, when the Army—now all-volunteer—was emerging from what Milley describes as its 'post-Vietnam malaise.' This was a time of war-fighting innovation, which Milley would champion as he rose in rank."
It wasn't a debacle or quagmire -- it simply was a temporary "malaise" to be overcome and an opportunity for ambitious, "innovative" soldiers to rise in rank.
Similarly, our experiences in Iraq and Afghanistan will be shaken off and any "lessons" will be quickly converted to new weapons systems.
The rest. . . just footnotes, if that.