or raise the same objection just saying it will drive businesses overseas and hold out for a global wealth tax.

That one is much easier to give teeth to though. Any individual or corporation who flees to an international tax haven will be barred from entering the US, doing business in the US, or participating in US markets.

Any assets in the US will be seized, any US protected intellectual property will be made public domain, etc.

How will California enforce theirs?

I could have sworn that it also included language that applied the tax if they leave the state, too, but even if that's incorrect, who cares? Let them move. The more states that do something like this, the less places they'll have as "safe havens" and if they move out of the country, cool, again, let them. It sends a clear message: If you won't pay your share, we don't want you here.

Once everyone collectively agrees that billionaires should pay their share, there will be nowhere left for them to run. It has to start somewhere.

While they are mentally unwell money hoarders, even by that standard it is a bit ridiculous to uproot your entire life over 5%. Even the wealthy have friends, family, places they like to eat, preferred hooker burial sites, etc... and losing ready access to keep some discretionary income that would leave you checks math still absurdly wealthy is bonkers. That and if they're moving a business it's a whole other can of worms. Yeehaw move to Texas and find out how crooked the state's regulations are and how a majority of people around you are not mentally developed enough to function in society- including maybe the person who cooked your meal or rotated your tires.

a state [tax] will just push billionaires to other states

I don't know about you, but I take comfort in that.

CORRECT! A ONE TIME Tax is going to ANNIHILATE the Major Taxpayers! Major Job Creators! People who pay the least tax while taking the MOST Welfare!

Historical consequences of a wealth tax:

In other words, it’s just bad tax policy, hard to track and introduces administrative burden, and encourages further obfuscation. Alternative: Income tax reform is a better solution.

In theory a federal one is better but it's unrealistic. It's going to be hard enough getting a state wealth tax passed, it's essentially impossible to get a federal one passed. For that to happen you'd need to give Democrats complete control of both houses of Congress and the presidency, and even then it would be a struggle. With Republicans in control of anything it's a complete pipe dream. So rather than going for the perfect solution that isn't going to happen anytime soon it's better to go for the imperfect one that has a good chance of actually happening.