the man has so much chess knowlege that he probably would be in the top 10 if he came back
And that's exactly the problem. For a large part of his career he was the undisputed #1, and if he came back he would "probably be in the top 10." So why should he come back?
the man has so much chess knowlege that he probably would be in the top 10 if he came back
p.s how does the rules work for elo if you retire and come back?