Hold up--by that logic, if a country has a military it should also be okay for its citizens to privately kill one another.
Or: "The government is allowed to print bills and mint coins that look just like the real thing, so why can't I?"
Regarding money, citizens however are free to mine non-governmental forms of money such as gold and bitcoin.
> It is misleading to go from having a military to killing as if they're the same. They're not the same.
Almost there! Now finish the job by taking that crucial "hey that reasoning is sketchy" insight and look at how it also applies to your original argument.
Ex: "It is misleading to go from having having a {national agency spying on other nations} to {casual theft} as if they're the same. They're not the same."