Why are the rich getting tremendously rich? Because the Federal Reserve has printed money at an astonishing rate, which inflates asset prices. Who owns the most assets? The rich do.
People are so focused on taxation (because it's something the average poor or middle class understands) when the real issue is the Fed (something most Americans aren't even aware of).
Still, the point still stand: federal income taxes are quite progressive, and would surprise most people who wave their angry fist asking for the rich to be taxed more. The problem is mostly at the state and local level.
The top 50% pays 97% of federal income tax.
If you include most types of taxes, including social security, you end up with something a little less polarized: the top 1% have an effective tax rate of a little under 34%, while the poors are around 20%. One could easily argue it's not progressive enough, but it's still not the usual narrative of "I pay more taxes than millionaires".
A a handful of ultra rich abuse loopholes to death to pay very little, and these people are averaged in the statistics (so the average rich person actually pays more than the stats show, if only a little). It's a minority though.
Don't you get the value of the money back for all taxation, according to any theory that approves of taxation?
Social security would be a little closer to a sewer and water bill from the city (which you have to pay if you're a owner, but you get a sewer in exchange. Whether you like it or not). It's still not a great analogy because Social security is more deferred. It's really its own thing. Still, it doesn't work quite like a tax either.
I personally wouldn't mind if it did though. It's one of those things where we'll pay for it one way or another. If there's an entire generation of people who can't properly retire and pay medical bill, we will pay for them through taxes anyway. May as well do it preemptively and efficiently.
Roughly speaking, anyone paying more in taxes than the per capita spending is probably not receiving the full value of their taxes. We see this where most welfare (Pell Grants, SNAP benefits, Obamacare, etc) and tax credit schemes (CTC, electric car credit, etc) phase out as people pay more taxes.
This is exacerbated by capital gains and dividends being taxed at a lower rate; if the gains due to asset inflation were being taxed at 37% instead of 15%, then at least all this money printing would help balance the budget a bit...
The top 10% of Americans own about 85% of the wealth in America, and the entire bottom 90% only own around 15% of it.
This was just last year. The norm is far lower, but was inflated by stimulus checks.