My own opinion on this:
1) Even though social security is called a "tax", it is more like a forced savings program -- participants pay in, and then they get an annuity by the time of retirement, somewhat related to how much they paid. Additionally, there is a little bit insurance thrown in called social security disability.
I would, therefore, exclude SS from consideration.
2) Beyond this, much of the income of people with considerable assets, is in form of dividends and capital gains. The long term capital gains part is taxed very leniently. Many business ventures or executive compensation, hedge fund manager compensation and so on, is arranged so that the gains are least taxable.
In addition to this, there are some tax maneuvers that may be illegal, but are practiced. Say, if you own a rental apartment, you could write off repair costs, and throw in some money you spent on repairing your own house. That is not legal, but hard to prove. It works only if you have a rental apartment.
This is what Leona Helmsley did, and she would get away with it, if she was not such an asshole and did not try to stiff her vendors.
The so called "charitable contributions" are also, often, nothing but a sham. I consider both "church contributions" -- which are basically fees to belong to a local social club -- and "dirty goodwill clothes donations", to be a form of tax scams, judging by what I see.
They are not a real form of charity, such as writing a check to a distant charitable organization like Red Cross or NRA Foundation.
So, it is not surprising that people with income, many assets, complicated tax situations, etc have a relatively low total tax rate.
Personally, I do not think that it is fair or sensible.
I would like, personally, to belong to the "wealthy" category, but, at the same time, I recognize the unfairness of this sort of taxation. I also do not believe the bullshit about how the wealthy will "stop working" if their taxes are bring in line with the marginal tax rates on ordinary income.
I would, personally, work just as much (or little) regardless of how my long term capital gains are taxed. In any case, a long term capital gain tax is discounted _even if_ it is at the marginal income tax rate, because it is only effective when securities are sold. I have some stocks that I own since 1996, and I never paid a dime of taxes on those.
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