The US Govt (at least on the Federal level) is mandated by the US Constitution to provide for defense...that is one of its few enumerated responsibilities and powers.
That's for *defense*. We send almost half our budget on defense, but maybe about 5% of our budget actually goes to defense. The remaining 45% is for buying expensive toys from defense contractors to assuage our tribal concerns that the country is undefended. Although we pay our soldiers burger-flipping wages (partly to justify not raising the minimum wage for actual burger flippers), the Pentagon is actually complaining about being overloaded with so much expensive equipment that they can't even keep all of it out of the rain. We aren't safe if our military can only end life on the planet- it should be capable of destroying three or four planets, and at least ten by 2030. That's not defense, it's a parasitic industry that gobbles up nearly half the budget. But people are so entranced by it-
guys like Brian Williams who ejaculate when they see a couple dozen Tomahawks being fired- that's almost always a cheap political win. Every government that does nothing for its citizens (e.g. North Korea) resorts to military displays. It's an opiate for the masses.
The Constitution was written when health care costs were not even a conceivable issue at all. For most of American history the Constitution has been considered a working document, designed to be amended as times change in ways that could not have been forseen. That was the 18th-20th century view of the Constitution, but it went out the window several decades ago. At this point, Americans have fetishized the U.S. Constitution like it's an appendix to the Bible, and they quote the Founding Fathers like they were apostles. When amending it is now considered sacrilege, it has completely lost its usefulness. You have the rights you have (and might have needed) up until this originalist attitude set in during the 80s. Now you will never be given any more Constitutional rights, no matter what changes in the near or distant future. Since health care only emerged as a serious problem in more recent decades, you'll never have a Constitutional right to free health care. But you can always kick a British soldier out of your house. That's fucked.