The vast majority of the increase in these people’s wealth over time is newly-created; it’s value that literally didn’t exist before, not an amount of cash money taken away from anyone else.
A wealth tax will go after that, and that will absolutely make sense. They can sell the shares they have in the companies, and that will make them think twice before cheating the system to grossely exagerate the value of their companies.
And if we talk about start-ups or other special cases where the CEOs can't sell shares and/or we don't really know their worth, we can have them give shares as payment. The gov will sit on them until they have actual value and sell them, or relesase them back if said value was lower than estimated at the time.