well, we sure as fuck pay enough money for it. At the cost of our healthcare/life expectancy/education.
You do realise this money doesn't leave the country right?
The US's massive defence budget funds US companies and US workers. The magnitude of the money also allows for really advanced R&D that otherwise wouldn't be financially viable to pursue.
As a result of this the following technology would not exist:
Computers (computing technology driven by military simulation needs)
Internet (need to network military commands)
GPS (track military movement)
Hard-drives (piezo electric crystal (the most important component of a hard-drive allowing for minute accurate movements) development was spearhead by the need for ultra sensitive sonar stations to detect Russian subs)
Aircraft technology (need for faster more powerful fighter jets leads to massive advancements in civilian jet liner technology)
Rockets and Space exploration (satellite technology and ICBM drove the space race)
etc etc
You could literally go on for days the amount of technology you take for granted every day which only came to fruition because of the vast almost wasteful military funding.
Please don't be under any impression all the money the US spends on its military is wasted. Sure there is waste, but when you look at such marvels as modern computing, space exploration and the internet ... I'd say it's worth it 10x over.