Pilots do not (or no longer) self-report mental illness at the same frequency because it effectively destroys their lives and career. One paper of many describing this phenomenon: https://pmc.ncbi.nlm.nih.gov/articles/PMC11302551/
An article, one of many: https://www.reuters.com/investigations/if-you-arent-lying-yo...
If you have any pilot friends in commercial aviation, you can just talk to them as well.