"Sure, sure. It's also true that no billionaire just sits on a giant pile of cash; most of Bezos' wealth is abstracted into stocks, investments, and so forth.
But that's not the scope of this simulation. This simulation is about spending all of Jeff Bezos' fucking money."
The game itself says about that. They don't think net worth = money you can spend, it's literally just a game where you get to think IF you could just spend stocks like money.