Why Can't We [Americans] Rein In This Ridiculous Military Spending?

Because politicians listen to lobbyists, is the answer in a nutshell.

So what if the F-35 fighter project has created 125,000 jobs in 46 states? Instead of spending that money paying businesses to build a weapon that works badly, we could spend it on renewable energy development and create more jobs, and achieve something useful at the same time.