California’s progressives are eyeing other people’s money. Again. The proposed “Billionaire Tax Act” would amend the state constitution to impose a one-time five percent tax on residents with a net worth above a billion dollars.

Supporters say it’s just a one-time levy for worthy causes. But experience says “one time” rarely means one time, and the unintended consequences are real.

The measure has yet to go before voters, but the threat alone has already pushed almost forty percent of California’s billionaire wealth out of the state. Gone. Along with it: income taxes, sales taxes, property taxes, and the charitable giving those individuals once supported.

Wealth is mobile. It goes where it’s treated well. And it’s not hard to see why.

California should remember that before it drives even more of its tax base away.