Why does the US military still fight & train like it's still fighting the 20th...

[Anarcho-Capitalist]

...century Cold War & not......... what certainly now looks like a 21st century dominated by guerrilla wars because no one is stupid enough to take on the US military in a conventional war?

Even in this day & age of the War on terror only about 5% of the entire US military budget is spent on US special forces & counter insurgency training while the rest of the US military is preparing for WW3 that will never come because if it does all the nuke weapons will take care of that war.

Are US military leaders so stupid that they don't realize all of that or can the US Defense industry not afford to lose those billons of US taxpayer dollars?