Steve Ballmer quitting as CEO increased Microsoft's market cap by over a billion dollars. If someone can be worth a negative billion I see no reason a different person can't be worth a billion. What you are worth and what you get paid aren't the same, obviously. That depends on outside options, how much beter you are than the next best, replacability, productivity. But while large companies do not revolve around a single person one person leaving can be worth more or less arbitatry amounts. Notch made a billion dollars prety much single handed.

Suppose person A has a 50% chance of making the right decision, and person B has a 70% chance. Person B is then worth paying up to $200M more. Or, if you end up making ten decisions like this per year, then even 52% vs 50% would be worth the same amount. When you're managing enormously valuable properties, even small increases in performance can be worth a lot.