A proposed tax on California billionaires has dropped like a bomb on state politics, splitting the Democratic party and galvanizing the state’s Big Tech executives in opposition. The initiative hasn’t formally qualified for the ballot yet, but backers have gotten more than 1.5 million signatures in support of it , nearly double the required 875,000. The threat of the tax has been enough to inspire backroom arguments, group chat strategy sessions, sudden interstate moves, a pro-billionaire march through San Francisco , millions of dollars in political spending, and apocalyptic warnings from California’s tech exec class, who make up some of the tax’s main targets. One AI entrepreneur declared the tax would be an “ economic 9/11 ” on the state and its tech industry. The debate, more than just a tax policy fight, is a referendum on the present state of opinion around wealth, taxes, and tech in California.…