The billionaires are spending mad money to fight this tax.

Mad for regular people money. From what I’ve read, what they’ve spent is a small fraction of what said tax would cost them (though if you’ve seen different, I love new info!)

A person is easy to move, a warehouse less so.

These folks don’t usually have warehouses, but whatever, say physical infrastructure. All that can stay, the boss can roll out, rock in Texas and take their private jet to and fro as needed. (Or, do their stuff remotely. I doubt Thiel is walking through cubicles etc.)

The worst case scenario for California of the mythical “Wealth Flight” is a bunch of parasites moving elsewhere.

The worst case is that the tax revenue that those billionaires bring (which sure, in a moral vacuum should probably be higher) goes elsewhere leaving California needing to plug the fiscal gap by taxing less wealthy folks or eliminating/reducing services.