> Start-ups and venture-capital investment could begin to flow to lower-tax states; the next hub of technological innovation may end up being seeded in Austin or Miami instead of Silicon Valley.

There is another agent (group of agents) in this game and that's other states. Those states are often modeled as passive background places one can move to, but they are often not. They can, and do, react to tax laws in other states. For example, TX could encourage capital flight by offering tax breaks.

I've seen this happen with some companies in Midwest: as the states had to raise taxes some Southern states decide to poach individual companies and offered them to move their HQs there with a bunch of tax rebates and credits and such.

> The tax’s designers, however, think they’ve come up with a clever solution to capital flight: a one-off tax that is retroactive, based on a billionaire’s residency status on January 1, 2026.

That is pretty clever. They could also have an "exit tax" -- "leave but if you've been here for 10 years making your billions, we'll keep some of those billions" kind of a deal.