Most Americans agree that the ultrarich should pay more in taxes. But this is often dismissed as self-interest: Tax reform is cutting my taxes, and raising yours.

You know something is seriously rotten about our economy, though, when even the billionaires argue that they should be taxed more.

This appeal to all the 2020 presidential candidates, released in a letter Monday, was signed by moguls who amassed their own wealth, like Facebook co-founder Chris Hughes, and those who inherited it, like Abigail Disney.

The problem, they all agree, is that in the face of profound inequality, huge sums are sitting around untaxed by the federal government, in assets like stocks, bonds, yachts, cars and art.

Like a $590 million yacht with a basketball court, owned by Hollywood’s richest man. Or a 14-foot tiger shark preserved in formaldehyde, worth $8-10 million, owned by the hedge fund manager who inspired the series “Billions.” You get the idea.

In general, we pay taxes when we earn or spend money, but not on wealth itself. As a result, the richest 0.1 percent will pay the equivalent of 3.2 percent of their wealth in taxes this year, the letter notes, compared with 7.2 percent paid by the bottom 99 percent.

“We are writing to call on all candidates for President, whether they are Republicans or Democrats, to support a moderate wealth tax on the fortunes of the richest 1/10 of the richest 1% of Americans — on us,” the co-signatories wrote. “The next dollar of new tax revenue should come from the most financially fortunate, not from middle-income and lower-income Americans.”

This isn’t about class warfare; it is about a moral, economic and patriotic duty, they argue. Income inequality has grown so extreme that even the uber-rich are taking a stand. It demands a new aggressiveness on the part of government, too.

President Trump promised he would help the middle class more than the rich, but in reality, his tax plan did the exact opposite. It’s like being told you will “transform your future” at Trump University, when all you get is a photo-op with a cardboard cutout of Trump, for $60,000.

Democrats, on the other hand, have a torrent of proposals to address economic injustice, including a plan put forth by Elizabeth Warren to tax wealth. Bernie Sanders, Pete Buttigieg, Beto O’Rourke and others have also come out in support of a tax on the wealthiest Americans.

“If you own a home, you’re already paying a wealth tax—it’s called a property tax,” Warren argues. “I just want the ultra-rich to pay a wealth tax on the diamonds, the yachts, and the Rembrandts too.”

They tried this in Europe, and rescinded the wealth tax because it was too difficult to enforce. The rich wriggled out of loopholes, hoarding their money in off-shore accounts, for instance. But Warren says her plan takes a lesson from that and includes stricter anti-avoidance measures.

Regardless, these and other promising ideas – like Cory Booker’s “baby bonds” to help close the racial wealth gap – should be at the forefront in the first round of Democratic debates this week.

More than 60 percent of voters say they support a tax on large amounts of wealth, including half of Republicans. This is probably because the top 1 percent of Americans now own about 40 percent of our country’s wealth — more than they’ve held at any time over the last half-century.

Trump was right to say the economy was “rigged”; it’s a pity that all he did was make it worse.

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