If your average folk's argument of "why are we spending one-trillion dollars on the military when X people are Y" were taken all the way to see that all government action is at the expense of higher-valued uses of said resources, then perhaps the allocations they desire could be realized on the free market they continue to despise.
This is indeed an exorbitant amount for our supposed "protection," which monopoly theory would easily tell us must rise in price and decline in quality, not to mention the ethics of being compelled to fund terrorism (or anything else you don't like). What will it take for them to not want someone else to spend their money for them anymore, in light of how it is misappropriated, or, expropriated, and to keep it rather for themselves?
If it's true said government service were beneficial, then it wouldn't have required coercion (taxation) to relinquish the money; they would have handed it over freely anyway. By their own admission they would seem to believe private business could operate selling governmental services and attract paying customers without compelling membership into such an organization.
Though utility, a subjective concept requiring the individual's assessment, cannot be added up and measured, we can still state on grounds of demonstrated preference, that, whereas all free and voluntary exchange is a mutual increase, all taxation and redistribution of property must mean a loss in utility. Only free and voluntary exchange increases the utility of both parties, i.e., is mutually-beneficial. It is taxation and other interventionism that is zero-sum, i.e., has an inured party, and therefore can never be said to raise total social utility.
But no such economic rationale as allegedly increasing utility or making the economy more "efficient" can be a justification for violating libertarian principle. Even if government could make us richer, which it cannot, we would still have to oppose it. However, we can demonstrate that even the utilitarian should be able to reach such conclusions of non-interventionism.
Whether by heightening time-preference and discouraging savings, thereby encouraging capital consumption, preventing capital from ever forming, inflating away money's purchasing power, manipulating prices, wages, rent, interest rates, starting wars, or forcing us to fund public schooling, we are made worse off by such policies.
The State, this non-market institution which decrees a monopoly over a given territory for a given good or service, which earns its income not by voluntarily selling goods but by employing coercion or aggression, is not for "the people"; and it does not exist to make us financially better off. Anyone who supports it is an unwitting apologist of relative impoverishment, where production, as arbitrarily decided by the State, is disconnected from the goal of satisfying voluntary consumer preferences that would be on display in the market.