Mark Cuban warns Ro Khanna: Only ‘idiot’ startup founders will stay in California

American billionaire Mark Cuban has issued a sharp warning to Representative Ro Khanna (D‑Calif.) over California’s proposed 5% billionaire tax, known as Proposition 40. In a lengthy post shared on social media platform X (Formerly known as Twitter) Cuban argued that the measure would drive startup founders out of the state, saying blunt that ‘only idiot startup founders’ would remain if the bill passes. The tax proposal, set for a vote on November 3, would levy 5% on all assets owned by California’s wealthiest residents to fund healthcare, schools, and food assistance programs. Supporters, including Khanna, frame it as standing up for the working class against the billionaire elite amid rising living costs. Cuban, however, warned that the policy misunderstands how startup wealth works.Mark Cuban’s argumentCuban explained that many founders of “Deca Unicorns” — startups valued at $10 billion or more — are cash poor but stock rich.