I don't think its that simple and is overly simplistic. If it was all about getting a better deal why wouldn't they have all left for Switzerland by now? Objectively, its a better deal than what the US offers - even on tax rates.
Everyone has their own tipping point. Just as salary isn't the only reason to move job, taxes aren't the only reason to stay. But at some point, people move. And the US makes you pay tax overseas anyway, so you can't just move and re-domicile. You have to emigrate and gain citizenship elsewhere.
Just within the US you could ask why wealthy people aren't all moving to states without any income taxes more frequently. Plenty do move to certain low tax states but network effects, infrastructure, stability, well-understood regulations, etc., seem to often play a bigger role.