I think your presumption is off. It’s not that threat actors won’t find them, but LLM tools rapidly increase the rate in which they can find them. It’s a bow and arrow versus a machine gun.
Its like a set of glasses that intentionally obscures the battlefield.
The defender industry is really far removed from seeing all exploits land on their targets all the time Some actors can get a long life out of an RCE that gets them privileged context, or a strong LPE. Its really hard to find out what someone did to get on a box if they attained root or system access and wiped their trail...
It is some assumption attackers need buckets of 0days to do their work. They might be somewhat saddened if a good sploit gets patched but they will have a few more laying around... unlikely they will have 10s or even 100s available and ready simply because it costs a lot and isnt needed.