A single bad actor trying to find a bug in order to achieve a specific aim, might mean that bug is never known by the software creator. However the majority of the public is also likely to not know about the bug.
Public hunting and exposure via security advisories, it's going to lead to a greater awareness of vulnerabilities which I imagine will increase the likelihood of a particular vulnerability being exploited.
The time and effort required to fix a vulnerability is often substantial.
Perhaps we shouldn't be categorical, in our assessment of the merit in finding vulnerabilities in software?