Mark Cuban slams California’s plan to tax the rich: Why he’s calling the 5% billionaire wealth tax ‘insane’

Mark Cuban thinks that everyone wants his money.

So joked the entrepreneur on a recent episode of https://www.youtube.com/watch?v=4Scbz7okkc4&t=1s" rel="noreferrer noopener" target="_blank">the Pivot podcast, explaining his recent online back-and-forth with Representative Ro Khanna.

Khanna is a big supporter of California’s Proposition 40, a measure that would levy a one-time 5% wealth tax on all billionaires in the state.

Cuban—to put it lightly—is not.

Earlier this month, Cuban wrote that Khanna’s plan for California’s wealthiest residents is “insane,” and his latest comments on the matter only made that stance firmer.

But how exactly would Prop. 40 work, and is Cuban’s stance justified, or just a knee-jerk response in defense of his fellow billionaires?

Proposition 40, explained

https://ballotpedia.org/California_Proposition_40,_One-Time_Wealth_Tax_for_State-Funded_Healthcare,_Education,_and_Food_Assistance_Programs_Initiative_(2026)" rel="noreferrer noopener" target="_blank">Prop. 40 will be on California’s ballot this November, where residents of the state can vote to levy a one-time tax on anyone in California with assets valued over $1 billion, including any stocks, bonds, and legal or equitable interest. 

With https://cabillionairetracker.org/" rel="noreferrer noopener" target="_blank">an estimated 259 billionaires currently living in California, the 5% tax has the potential to raise tens of billions to be put toward public services.

That money would be put into two funds: 90% would go to the Billionaire Tax Health Account, which would fund Medi-Cal and other health coverage programs, and 10% would go the Billionaire Tax Education and Food Assistance Account, which would fund food assistance programs and K-14 school meals.

Those affected by the tax would have the option to pay the full sum with their 2027 tax filings, or to split the amount into equal payments across five years, starting in 2027.

“Passing this ballot initiative will ensure that millions of working class and middle class Californians won’t lose their healthcare,” Khanna said https://x.com/RoKhanna/status/2088688763723469266">in a video promoting the measure. “What this shows is that California voters want a Democratic Party that will stand up for the working class over the billionaire class.”

Khanna and Cuban go at it online

https://x.com/mcuban/status/2088720475643949237?s=20" rel="noreferrer noopener" target="_blank">Cuban responded to Khanna’s video on X, saying that Prop. 40 would devastate the unicorn start-ups that flock to California, which he wrote “are the definition of cash poor, stock rich.”

“Do you really think each of multiple founders, who started an amazing company in Cali and is now a billionaire, can each just pull out $250m per billion of net worth from their raise?

You know they can’t,” Cuban continued.

He added that the measure wouldn’t impact him personally, as he’d leave California before Prop. 40 took effect if it passed. “But you can bet if I’m investing in a multi billion dollar startup, I’m asking them to move from California first,” Cuban wrote.

From there, Cuban and Khanna exchanged post after post, including https://x.com/mcuban/status/2088787419906576436?s=20" rel="noreferrer noopener" target="_blank">Cuban calling Khanna’s plan “insane” and “the biggest fuck you in the history of entrepreneurship.” (That https://x.com/mcuban/status/2088831412950458392?s=20" rel="noreferrer noopener" target="_blank">latter post contains five more expletives aimed in Khanna’s direction.) 

Cuban doubles down

Off of social media, Cuban got the chance to talk through his position on Pivot with host Kara Swisher, pointing out that many billionaires, by the measure’s definition, don’t have access to 5% of their wealth, especially if they recently became billionaires through investments in their start-ups.

“People don’t realize that a billionaire doesn’t mean you have a billion dollars in liquid assets,” Cuban said. “If you have a company that’s valued at $10 billion, and you have three founders that each own 10%, they’re billionaires by the state of California’s definition.

The chances of them having $50 million in cash are zero.” 

Cuban continued that he thinks the tax is “ridiculous” and will end up driving companies—and the jobs they provide—out of California.

But Prop. 40 is popular in the state, with https://news.berkeley.edu/2026/08/17/california-prop-40-the-billionaire-tax-holds-lead-in-new-uc-berkeley-igs-poll/">recent polling showing that 48% of Californians support the measure while only 41% oppose it.

When Pivot host Kara Swisher brought up the measure’s popularity to Cuban, he took it in stride.

“Everybody wants my money,” he said with a laugh. “I’m fortunate: Usually they say they’ll eat me last.”