There truly are few ways to waste taxpayer dollars more thoroughly than on the military.
Social security goes from taxpayer to retiree often to be spent immediately at market for goods and services useful to many fellow countrymen.
Medicare removes the burden of caring for your elderly from the lives of millions. Its a huge economic boom to not have your parents retirements costing you your time and productivity.
The military, the third largest expense, has three principle benefits - its a direct jobs program for ~3 million people (the enlisted proper military and their tertiary federal contractors supporting them). It keeps in business a dozen or so arms corporations that use their revenue to lobby congress to spend more on the military to make themselves and their investors more money. And it projects American power abroad to use gunpoint as a weapon of trade negotiation and to "maintain the peace" (even through ideological warfare) in our zones of trade globally.
The first two are obviously awful for what purpose they fulfill in a vacuum - you could much more cheaply just house 3-5 million people and give billionaires free money instead for a fraction of the actual cost of maintaining the US armed forces. And as a US citizen the idea that my tax money goes to maintain peace in the world for the benefit of all of mankind might be passably acceptable if there were no other choice, but organizations like UN peacekeepers exist (though palpably suck at) fulfilling a similar role except without the bias towards US economic interests. Perhaps without this one nation acting as world police collaborative organizations could fill the role, but probably not.
So it comes down to a moralistic argument - is it worth it to waste the time of millions of Americans to perpetuate a theater show dick waving competition with hostile dictatorships like Russia and China around the world for the express purpose of maintaining US economic imperialism. Because its really up to you - we slaughter hundreds of thousands of innocents in deserts and huts the world over but in exchange few nations have the spine to try engaging in organized warfare amongst their neighbors for fear of US intervention. There are benefits, its just if the costs we pay, and continue to pay and more each year, especially when any benefit that could generally be perceived as of universal benefit are things I would at least more generally like to see all of humanity not only pay but participate in the management of are worth it.