Neil Rimer doesn’t sound like most billionaires. When the Index Ventures co-founder sat down in Athens last month, he dismissed the quarter-zip uniform of his peers and delivered a warning that still rattles: the staggering wealth piling up around AI will be redistributed. “It’ll either be voluntary or it’ll be involuntary, but it’ll happen, and I hope it’s voluntary,” he said, adding that tech leaders “can play a leading role in seeing that through.”

Coming from a man whose firm just netted an estimated $9 billion from exits like Figma’s IPO and Google’s Wiz acquisition, the statement lands differently than standard populism. Rimer has skin in the game. He’s also got a track record of giving — he chaired Human Rights Watch for six years and his family donated $13 million to McGill University — but he’s increasingly an outlier.

The Giving Pledge, Warren Buffett and Bill Gates’ 2010 challenge for billionaires to commit half their fortunes to charity, is gasping. Just four families signed in all of 2024, down from 113 in its first five years. The broader numbers are worse: only half of American households now donate, down from two-thirds in 2000, and even affluent giving has slipped from 90% to 81% in seven years. At Anthropic, one of Index’s portfolio companies, a financial planner told Business Insider that newly minted millionaires aren’t building philanthropy into their plans. “That’s what I’m seeing more than the desire to become philanthropic,” Alex Caswell said. Most want to angel invest or start companies.

California voters will decide this year on a 5% one-time wealth tax targeting billionaires. Some, like Google’s Sergey Brin and Larry Page, have already decamped to Florida. OpenAI is reportedly eyeing a 2027 IPO — cynics note the tax calculates net worth based on worldwide assets at the end of this calendar year. The company has also floated handing the federal government a 5% equity stake, a move CEO Sam Altman frames as sharing AI’s upside but critics read as buying political cover. Veteran investor Roelof Botha joked last year that “some of the most dangerous words in the world are: ‘I’m from the government, and I’m here to help.’” Rimer’s prediction hangs in the air, and the clock is ticking on the voluntary part.