It sounded like NSO group just considers loosing zero days like this a cost of doing business.
There seemed to be an implication that they have a war chest of these exploits and expect them to each get burnt after a certain amount of usage.
That's exactly what it is. These companies buy, research and stockpile exploits, and keep a few always at ready for when the currently deployed ones get burned. All exploits have a shelf life, and the more widely one is used, the more likely it is to get caught.
Because let's not forget: NSO and their ilk are not in the business of developing exploits. That's just their raw material. They are in the business of selling weapons-grade espionage and surveillance capabilities.