Think about it, what are taxes for? To pay for all the things we share as a people: government, roads, healthcare etc.
If we're getting an equal amount out of the system why is it fair to expect people to pay different amounts into that system. Think about it, If you go out for dinner with friends and all eat the same amount you wouldn't expect to pay the bill based on your incomes.
That's why if you really wanted a "fair" system everyone would pay a flat dollar rate, such as $5000/person. I realize that's not realistic but perhaps we could meet in the middle with a flat tax rate, which would mean rich people would be paying WAY more than poor people. Don't even get me started on tax brackets, you're taxing people for being successful? That's just legalized theft and beyond mental.
Also, why do we never question income tax? That's a relatively new invention, you're telling me I now have to pay money to make money and then ALSO to spend money? That's fucked up, it's double dipping by the government and it's immoral.
How does it benefit the rich?
With a flat tax rate someone who makes 1 million/year pays 10X more taxes than someone who makes a hundred thousand.
The rich pay taxes at an unfairly high rate.
Don't forget that the current tax code is written for the rich - you may see the top bracket is higher, but anyone that is smart is funneling their money to avoid taxes. For example, the nominal tax rate of a married couple making $120k/yr is 22%, or ~$26k in taxes every year.
But, the couple will use the standard deduction ($24k), and use some pre-tax deductions, such as 401k and HSA contributions, meaning they only pay 4% in taxes or about 5k. They have to throw almost half of their money - about $50k - into tax advantaged accounts - meaning they only have less than half of their income (about 55k) to spend on what they want. Honestly, it's basically enforced social security. Either pay 26k in taxes or save half your money for retirement. "free country"...
You want people to prefer saving money over spending it? Then put a sales tax on everything instead. I highly encourage saving, but my frustrations with 401k/ira/hsa are the complications behind it, and the # of "gotchas" waiting for you. You shouldn't be taxed for wanting to save for a down payment instead of retirement. Owning a house is a decent way to secure your money while having a place to live.
The more money you make, the less you have to follow the normal "rules" and you can start following the harder ones to follow. Business deductions galore.