To me, "it's all mental" is like an NBA player missing their free throws (or any other professional screwing up something basic due to not focusing or the moment getting to them). Having a physical brain difference from the general population does not qualify as being "all mental". The problem is physically in the brain, not an idea you created that is causing the issue. The same way depression isn't "all mental", depression is the physical manifestation of an abnormality (chemical imbalance) occurring within the brain. Same thing.