Google also isn't (mostly) funded by taxes. It makes sense to be more concerned with what someone does with my money than what they do with their own money.
Yet money is the product of a social contract, both in its very existence, and in society's defense of private property. Moreover, it only has value relative to the social ecosystem that can exchange it for tangible value. Countless agents, whether public or private, are capable of increasing or decreasing the value of "your" dollar without ever removing it from under your mattress. If the value decreases due to a market failure, did they steal from you? Hypothetically, if someone took 10% at gunpoint, but invested it in a way increased the net value of the remainder by 50%, how about then? It is effectively impossible for private property to live in a social vaccuum in an industrialized economy.
All that said, I'm sympathetic to that knee-jerk feeling. Writing large checks to "United States Treasury" is merely unpleasant. Knowing that those checks pay for missiles that murder children is infuriating.
By "my money," I only mean money which my employer agreed to pay me for performing certain tasks. Obviously the philosophy of property rights can get really complicated, but I'm not making some deep philosophical argument. I believe this phrase in this context is pretty standard and likely to be understood by the vast majority of readers: it's money that my employer agreed to pay me if I perform certain tasks.
I never mentioned the word "steal" in my comment. I'm not very interested in a semantic argument over that word, so I'll just describe my taxes very simply: if I had the option to keep everything that's deducted from my paycheck without facing the high likelihood of legal trouble, I would. I'm not making a moral argument about "stealing" or anything else, I'm just stating my preferences.
The stuff about value being subjective and money being potentially devalued through broader economic circumstances is true, but entirely irrelevant. I would still choose to keep my entire paycheck if given the option.
I disagree with your description of my preferences as "a knee-jerk feeling." It's not that, by a long shot.
> I would still choose to keep my entire paycheck if given the option.
Is this preference influenced at all by where the money goes? You seem to state that you want to keep your whole check regardless (which is reasonable), and yet you feel you have a stake in how it is spent after it has been taken from you against your will.
That's kind of a tricky question, because if I say I'm okay with my taxes being on used on things I approve of, that's equivalent to saying I want to keep my entire check and then use parts of it to pay for those things I approve of.
Anyway, whether or not my views constitute a belief that taxes are not "legitimate" is a largely semantic question. The very notion of legitimacy borders on moral arguments, which I try to refrain from making. I could point to some distinctly libertarian arguments for the morality of taxation, some of which seem convincing if taken on their own terms, but that's not really my thing.