I’m curious how you came to that conclusion. While he’s certainly not in the pantheon of best presidents, he ends up around the 75th percentile in rankings by historians. Even subtracting a few spots, he’s nowhere near close to “one of the all-time worst“. Or are you faulting him for not resigning when incapacitated by a stroke?

https://en.wikipedia.org/wiki/Historical_rankings_of_preside...