According to one estimate, wealthy couples in NYC need $190 million to keep their heads above water

• Most people have a "happiness number" — the amount of money they need to afford the lifestyle they want and not worry about money.
• For a wealthy New York family, that number ranges from $100 million to $190 million, according to an estimate by Town & Country magazine.
• Only 0.09% of America's millionaires are worth over $100 million, a WealthEngine report estimates.

Even rich people think wealth is elusive.

About 5% of Americans are millionaires. Most of them — about 95%, according to an estimate by WealthEngine — have between $1 million and $5 million.

And many think that's just not enough.

"Many people believe that, along with tangible assets and services, having it all means having some wiggle room — money to cover a major splurge or setback, and more on top of that," Norman Vanamee wrote in Town & Country magazine.

Vanamee consulted experts to estimate the "happiness number" for a hypothetical, wealthy, non-working couple in their 40s with two teenage kids in an expensive private school in New York City. They live in a parkside Fifth Avenue apartment, buy art, take private jets, donate to charity, and have a household staff — a chef, a driver, and a housekeeper — plus two vacation homes. They're also setting aside $25 million for each child to inherit.

An analyst from US Trust cited in the Town & Country report estimated the hypothetical couple would need to have a net worth of $190 million to sustain this lifestyle.

Here are some of the costs considered in the estimate:

• Real estate: $18 million apartment on Fifth Avenue facing Central Park, $2 million for furniture and decor, $20 million for a weekend home in the Hamptons and a vacation spot in the Caribbean.
• Education: $1.7 million a child for a "no-expense-spared educational strategy," which includes private school and tutors, music lessons, sports, trips abroad, and four-year Ivy League tuition.
• Philanthropy: $25,000 annually to sit on the board of a New York City museum, plus $15,000 a table at annual charity events.
• Staff: $190,000 annually for a driver, a chef, and a housekeeper.
• Art: $20 million to $100 million apiece in a seven- or eight-piece collection, or about $1 million annually.
• Health and beauty: $150,000 annually for wardrobe, grooming, trainers, and cosmetic procedures.

Other experts peg the happiness number at about $100 million.

Billionaires "view $100 million as the starting point for real money," Richard Kirshenbaum, the New York Observer columnist who wrote the book "Isn't That Rich? Life Among the 1%," told Town & Country. "They call it a hundy. Like, 'Oh, they made it, they have a hundy.'"

Kirshenbaum says the estimate isn't his own but came from several billionaires he has interviewed. WeathEngine estimates that 0.09% of America's millionaires are worth more than $100 million.

But Robert Frank, the wealth editor at CNBC who hosts the TV series "Secret Lives of the Super Rich," said the number was "less relevant than how you earned it and what you're doing with it."

Still, having money doesn't alleviate all anxieties — in fact, it often gives way to new worries unique to those flush with cash.

"I still feel, to some extent, that I don't have enough money," Thomas Gallagher, a multimillionaire, told The New York Times. "Emotionally, I don't come from money; I got very lucky on Wall Street. I've been dealing with a myriad of psychological issues since I retired. I have more money than I had ever imagined, but I still worry

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