The richer and more income they make, over the standard deduction or itemized deductions, the more they pay....and the more income they have to pay without worrying about food for their family and a roof over their heads....
The 50% that don't end up paying in, don't earn enough "profit" to pay taxes on it...the profits so to say, would be income over and above what it takes to run a basic household....people who don't pay taxes is simply because they don't earn enough to have excess, to have a profit to tax once they take their living deductions, ...the standard deduction is applied to their income.
I'm pretty certain those 50% that don't earn enough to have more than they need to survive, would gladly...ecstatically pay the taxes the top 1% pays in order to have their income.