I agree but let's say, again for arguments sake, that I work hard to keep my health up. I eat properly, I live healthy etc etc and I got a health insurance just in case. Why should my tax money be spend on people who drink, smoke and lunch and dine at McDonalds without working out?
Sin taxes are supposed to cover the added costs of these things, though obviously in the US this is more true for smokers, middling for alcohol (small amounts are even beneficial) and not at all for fast food (but the actual causes of the obesity epidemic in the US are only now being worked out - and it has little to do with overeating).
Spend my tax money on people who really need it and who 'deserve' it.
I've seen libertarians seriously argue for not funding vaccinations or infectious disease containment.
And they root for defunding America's only method of actually combating bioterrorism.
The point I'm trying to make is you either treat everybody as (roughly) equal, or you treat them as different as they are. Not a bit in between like I feel is going on now in the US.
If it weren't for our military expenditures, we could probably get away with nothing more than healthy taxes on unearned income, a modest amount of sin and property taxes (in particular, intellectual property and radio spectrum), small tariffs (I support free trade in general, but I do think an e.g. flat 5% global tariff would help boost local stability and independence in general - and would consequently be a good thing), and revenue from government services and the Federal Reserve.
Right now, though, we give unearned income ridiculously preferential treatment, and a lot of benefits programs are designed as traps to keep the extremely poor 'content' and fighting against the middle class rather than outright rioting or working to escape their condition.