I would dispute it. One of the main public benefits, if not the main benefit, is protection of property rights. Those with the most property disproportionately take advantage of this protection.
Are you deliberately confusing taxes with federal income tax?
Are you trying to imply that the people who don't pay federal income tax have heavy state tax burdens? Or you think they're making a dent with their sales tax contributions? The only thing that everyone pays indirectly or directly is property taxes, which averages to about 1-2% of income. Again, nothing close to federal income taxes (for those that pay them).
Also this completely handwaves the regressive nature of sales tax, which hits much harder when you spend a large percentage of your income
According to the SF Chronicle, about 72 million US households (40% of the population) paid no federal income tax in 2022. I don't have exact numbers but I doubt anyone would dispute that public benefits flow disproportionately to those 72 million households for obvious reasons. So the cause and effect of being a citizen and paying taxes is very tenuous.
> Where exactly is the unsustainable part of this?
If it's unsustainable, then someone should propose a constitutional amendment to fix it.