This is demonstrably untrue, unless you are claiming that Amazon is only profitable because Bezos owns a huge portion of it and/or only runs the company profitably because he owns a huge portion of it.

If Bezos were taxed massively and had to sell a huge portion of his holdings, the value wouldn't go down, it would stay the same, just in different hands.

There is no logic that says a corporation can't function if it is not held by one person.