Who is the wisest person alive?
Would we even know about them? — perhaps by virtue of being the wisest, they are well off our radar.
This is obviously not a “testable” idea about wisdom — we can’t assess the wisdom of someone we don’t know about.
But claims based on good explanations don’t have to be testable (only scientific ones do, and they are just a subset of good explanations).
For instance, if the economy collapsed tomorrow so that space travel was no longer feasible, the claim “I would die in space without a space suit” would not be testable. But that doesn’t stop it from being a compelling claim, as long as it’s based on a good explanation — involving the body not getting enough oxygen to meet its metabolic requirements.
(A good explanation is one which describes what’s going on as comprehensively as possible and where all the details included perform an essential explanatory function).
It’s plausible that after examining the lives of the wisest known people we would find the principle that the less public attention, the better the quality of life. Furthermore there could be a trend that the wisest known people got their fame by accident; they were intent on staying anonymous until serendipity placed them in the history books.
If public attention had the largest aggregate of seductiveness before you have it and pain after you have it, then not wanting it (and managing to avoid it) would be the ultimate criterion of wisdom.