The only reason you're calling my question re: how much is enough for the "wealthy" to pay in taxes "nebulous" is because you know the answer is what's nebulous -- not the question.
You can't name a number, percentage or relative amount because THERE ISN'T ONE. All the tax rates, ceilings and limits, including deductions and exemptions, are arbitrary. Some finance "experts" in the government sit down and try to figure out what balance of those elements, along with deductions and expected revenues, will generate the needed revenues to pay the country's bills. There's no magic number that's fair -- not for the workers to pay, and not for the "wealthy" to pay. I put quotes on wealthy because that, also, is open to arbitrary interpretations based on relative income/wealth.
The problem you have is understanding the simple fact that the wealth created in this country has an effect other than making people who own the investments profits. They create jobs. People with jobs pay taxes. They sell things. Retail collects more taxes. They provide capital. Capital permits renting buildings, building new buildings, renting and buying large equipment, manufacturing that equipment, etc, etc, etc. All those activities get taxed at all points exchange and at many levels.
With all that taxing going on, you still believe the person making it all possible should be punished MORE than the people earning a paycheck? Take away the incentive to invest, and those paychecks stop. But you still won't get it.
You have been brainwashed into resenting the wealthy. I get it. You don't.
I'm done trying to open your eyes. Can't make a horse drink.