All criticisms are valid as this was a spur of the moment decision to create a very quick and simple survey in light of recent events. With all the criticisms in mind; if you even assume the percentages are way off, it still leaves a relatively massive percentage of pilots who are having issues.
A quick google reveals rough numbers of around 70,000 - 100,000 commercial pilots working in the US. Same rough numbers go for Europe. If the issues raised above only affect 10% of pilots then we are talking 7,000 - 10,000 pilots in the US and the same goes for Europe.
I would contend that the Class 1 Medical is not applicable in any way to mental health. At best it’s a moderately effective physical check on the initial issue and a very weak check on renewal each year. And the reality is that standards for renewal vary wildly with different jurisdictions. You can be fit to fly in one state and operate into another state where you would have your licence revoked. In the most basic case - retirement age varies even within Europe.