Should he retire? Of course he should, the story doesn't get better from here. Retiring in your hometown after a hard fought battle around the people you love.
Does he actually have the 1.5mil-3mil invested to support his lifestyle without ever having to work again?? Almost certainly not
Has he saved or invested any large portion of his earnings the last 5 years?? I hope so, because it's sad when you devote your life to being a fighter, destroying your brain and body in the process, and after all those years you don't have enough to retire and have to pick up an entry level job.
I wouldn't mind at all if he called it quits, he has given us so many great fights and moments. I really hope he can have a good retirement one day and provide for his wife and children with the best life possible.