"Asinine"?
You are clearly unaware that the United States military relies heavily on satellites, and where those satellites are located. So I'll help you out. They're located in orbit around the earth, which is also known as SPACE.
So unless you want those satellites taken out by an enemy like Russia, or China, or even a punk rogue nation like North Korea, it's probably a good idea to have some way to protect them.. in SPACE.
If you had been around after the air plane was invented, you'd probably say something brilliant like... hey Gomer, we don't need no fancy Air Force, because our president is an idiot. (actually, it was Army Air Corps, to be more accurate.)