I recently asked a wealthy political donor why he was supporting Bill de Blasio and his attacks on the wealthy.
"Because inequality is a problem in New York," he said. "The rich have gotten their way for too long."
By "rich" of course, he meant people richer than he was—as in billionaires. Inequality in New York is all relative.
The tensions between the rich and super rich, and between Old Money and New Money, are as old as wealth itself. But in New York, San Francisco, London, Hong Kong and other concentrated wealth centers, the growing gap between the rich and super rich has rarely been wider.
In an entertaining piece in the New York Observer, Richard Kirshenbaum writes of a friend (whom he doesn't name) who no longer feels important in New York because he's only a millionaire. It's what Kirshenbaum calls the "millionaire malaise."
"I'm 1990s money—in a new age—with one less zero," the friend says.
(Read more: 'Don't hate me because I'm rich' student: a fake?)
Now, it takes at least $100 million to matter in New York. He says he feels like a "loser" because of his $10 million apartment. His wife's 8-carat diamond is out-blinged by a friend's 20-carat rock. He's proud of his floor seats; another guy buys the team.
"You think you're a player, flying your family first class, then so-and-so asks for your tail number, and they look at you like you're taking the bus because you're flying commercial," he says.
Of course, no one should feel the least bit of sympathy for the underloved millionaires or the emotional pain they suffer for being Lear-less. Ask any of the more than 11 million out of work what it means to feel economically powerless.
But the millionaire malaise stems from a rapid growth in inequality—not just between the 1 percent and 99ers, but also between the 1 percent and the 0.0001 percent.
(Read more: What gives? Millionaire optimism soars to new high)
A paper by Scott Winship at Brookings shows that the "poorest" household in the top 0.01 percent had nearly 17 times the income of the poorest member of the 1 percent.
If the U.S. income structure were a building, he said, it would look more like the spear-shaped Burj Khalifa hotel in Dubai rather than a pyramid. If the top 0.1 percent were on the 160th floor, the top 1 percent would be on the 10th floor. And if Larry Ellison were on the 160th floor, Mitt Romney would be on the 6th floor and the rest of America is mixing with the top 1 percenters on the lower floors.
"The 99.99th percentile now sits on the third floor and the entire bottom 99 percent—and then some—mill around the lobby," Winship writes. "We are the 99.99 percent?"
With the new, soaring glass towers going up in Manhattan with $90 million penthouses, it's not hard to imagine that those living "below" in the prewar palaces along Fifth Avenue can actually feel disadvantaged.