When the grand vacation homes of Newport Beach were empty on a beautiful Memorial Day weekend, Molly Munger decided it was time for the US to consider taxing wealth.As her family’s boat moved through the harbor a few years ago, Munger, whose father is a billionaire investor, saw that many of her neighbors’ houses were sitting dark and vacant. She knew why: The owners now controlled enough money to holiday at one of their several other luxury homes. It didn’t sit right, she said. “It’s just too much to watch that happen at the top and see what is happening at the bottom,” said Munger, 71, a California civil rights lawyer whose father, Charlie, built his fortune as vice chairman of Warren Buffett’s firm Berkshire Hathaway. “Isn’t it a waste when beautiful homes on the beach are empty for most of the summer?”Munger is now among a handful of billionaires and multimillionaires making a renewed push for the government to raise their taxes and siphon away some of their holdings. As Democratic presidential candidates debate a new tax on wealth rather than on incomes, this group of uber-rich people is urging them on. “I believe in free markets. I’m the daughter of a capitalist. But not Darwin-like free, unregulated and red in tooth and claw,” Munger said.The chief argument from these tycoons, financiers and scions is that the government could spend their money more effectively than they could on their own by improving schools, upgrading infrastructure and protecting the environment. It challenges a long-standing belief among many politicians and economists that lower taxes on corporations and investment incomes are the most efficient way to deliver growth and spread wealth down the income ladder. The idea also is a direct challenge to the reputed billionaire in the White House, Donald Trump, who once backed a wealth tax but in 2017 enacted a dramatic tax cut that favored the rich.Twenty people, including one who remained anonymous, signed on to a letter this summer essentially asking to be taxed more. The group included financier George Soros, Facebook co-founder Chris Hughes and heiress Abigail Disney, and others often involved in liberal causes. Bill Gates, the world’s second richest person, didn’t sign it but has since said he “wouldn’t be against a wealth tax” on a net worth that roughly exceeds $100 billion.While Democrats have long pushed for higher taxes on the top income tiers, the current debate goes further — whether to impose annual taxes on what people own, not just on what they earn.