On Thursday, the House of Representatives passed, by a 227-205 margin, its long-awaited tax reform plan, dubbed the Tax Cuts and Jobs Act. Beaming Republicans praised it as a great boon to the economy and the middle class.

The plan would permanently slash corporate tax rates to 20% from the current 35%; reduce the number of tax brackets; eliminate personal exemptions while doubling the standard deduction and child tax credit; cut rates for some “pass-through” businesses, and end the alternative minimum tax, and phase out the estate tax.

To recoup enough projected revenue losses to get the bill through the Senate, the House plan would end deductibility of state and local income taxes and cap the amount taxpayers can deduct for medical expenses, mortgage interest, and property taxes.

Also read: Here are the winners and losers from the tax bill the House passed

Still, the respected nonpartisan Penn Wharton Budget Model projects that even under the most optimistic scenario, the plan would raise gross domestic product by 0.4% to 0.9% by 2027 but would blow a $2 trillion hole in the national debt.

It may have an even more profound effect: It would richly reward dynastic wealth and entrench an American oligarchy in ways we’ve not seen since the Gilded Age of Rockefeller, Carnegie and J.P. Morgan.

In that way it would, ironically, vindicate the theories of Thomas Piketty, the left-wing French economist at the Paris School of Economics, who, along with colleagues Emanuel Saez and Gabriel Zucman (both of UC Berkeley), has done massive research demonstrating the widening gap between the very wealthiest and everyone else throughout the developed world.

Piketty’s famous (and, in my view, simplistic) theorem r > g claims that by its nature, r, or the return on capital, increases faster than g, or GDP, especially when the population isn’t growing much. (Economists say GDP growth comprises population and productivity growth. When both are rising slowly, as they are now, GDP growth is reduced.)

In Piketty’s perpetual motion machine, the very wealthiest keep getting richer while the rest fall further and further behind. In his 2014 best seller, “Capital in the Twenty-First Century,” he repeatedly referred to the “rentiers,” coupon-clipping inheritors who, he said, rule the roost in his native France. “In a quasi-stagnant society, wealth accumulated in the past will inevitably acquire disproportionate importance,” he wrote.

What's Next For the House Tax Reform Bill?

But there was one glaring exception: the United States. I don’t think too many of Piketty’s fans or critics slogged through his whole 700-page tome, but I did, and right there, hiding in plain sight, Piketty struggled to make his theory work for the greatest capitalist society of all.

He called the U.S. “a very inegalitarian society, but one in which the peak of the income hierarchy is dominated by very high incomes from labor rather than by inherited wealth.” Echoing his critics, he ultimately conceded, “Over the long run, education and technology are the decisive determinants of wage levels.” Translation: The U.S. is largely a skills-based meritocracy.

But now comes the GOP tax bill, which may reverse that in several ways:

• The threshold for paying the estate tax would nearly double and would be phased out over six years. That would be a $20 billion a year windfall for the very wealthiest people, with estates of $11 million and more. Only 5,500 estates will pay those taxes in 2017, the Washington Post reported.

• It preserves the tax code’s “step-up” basis, which allows estates to value an appreciated asset not at its purchase price but at its current value, thus avoiding capital gains taxes on years of profits. So, someone who bought Amazon stock AMZN, -1.78% after its 1998 IPO or a Manhattan office building in 1985 could pass that on to his heirs without paying a penny of taxes on investments worth dozens or hundreds of times more.

• The massive tax cuts on corporations, along with reductions in the tax rate on repatriation, will be a boon to corporate America, but we have no idea if they’ll create more jobs or boost wages. They’ve already helped stocks skyrocket by more than 30% since the election, however. As of 2013, the top 1% owned 38% of all stock shares, according to Edward Wolff of New York University.

• Meanwhile, the rate on “pass-through” entities (partnerships, LLCs, and S corporations) that aren’t taxed at the corporate level but pass income through to personal tax returns, will drop to 25%, and again, the wealthy are prime beneficiaries; doctors, lawyers, and other service professionals are explicitly excluded from the lower rates.

The GOP tax plan may well have other benefits, and I support a corporate tax cut, but not one this big and that costs this much.

Yet this bill overwhelmingly helps the very wealthiest Americans and their heirs and moves the U.S., which likes to think of itself as an egalitarian nation, towards becoming the society of rentiers that Piketty has chronicled in his native France.

“Let them eat gateau” indeed.