You do a structured sale overtime and those do take place even in the billions of dollars without destroying the value of the stock. Also, they can borrow against the value of the stock, usually for extremely low interest rates, to quickly infuse cash. This argument is nonsense. The best recent example is elon buying Twitter. Yes it hurt tesla stock in the short term but it is almost back to the presale value with little impact on his overall networth. The wealth in stocks is very real.

Edit: The elon case isn't even a good example because he was forced to sell the stock much faster than normal.