Yes but not entirely. Yes in that if the CEO tries to sell 125B dollars of shares, the stock price will take a significant hit.
No in that this is paper wealth that you can borrow liquid cash against. Which makes a decent fraction of that wealth actually accessible (if you don't use this borrowing to just buy more shares.)
All wealth is paper wealth. The value of anything and everything changes with the wind and, as such, can only be measured at a moment in time. The ridiculous mantra that wealth isn't truly wealth until it is turned into cash is absurd since the value of cash itself fluctuates with rates of inflation and one currency against another.
