I agree, players really should retire sooner, but I understand many stay to finish out various corporate contracts, have their kids see them play tennis, give employees time to line up other gigs, & squirrel away extra cash for the college fund. Others become so institutionalized from Juniors onwards, it's all they know. Tennis
is their identity.
Once Monfils made those uncharacteristically negative comments about how he sucks, I knew the writing was on the wall. We often talk about injuries and age playing their part, but once you go mentally, it becomes impossible to win.
This narrative of the magic, fairytale run bookends so many careers, but also keeps players hanging on far past their so-called sell/use by date. Venus should've retired after 2017, Serena after 2019, and Nadal after his final RG. There are others to mention, of course. None of the players leave the game with the audience wanting more.