Biden was a horrible president - or whoever was running the White House I should say. But I will still argue that Jimmy Carter was the worst president in my lifetime, and maybe in history. Both of these men were president for only 1 term and both presided over some pretty bad crises of their own making. But Carter had more and much worse than Biden. Maybe it was just happenstance but I still think he was worse.
The Iranian hostage crisis, the Cuban boat people that result in a decade long violent crime spree in Florida and elsewhere, the Haitian boat people crisis, double digit inflation, interest rates hitting 20%, the worst violent crime rates in many many years, and he blamed it on the people of the country! This was all in 4 years and I am sure I am leaving more stuff out. This has nothing to do with personality, character or intelligence. Carter was supposedly a very smart guy. This is purely about how he ran the country and it was a disaster.
Biden had the border crisis, inflation, and some terrible foreign policy failures. These put him in second place for sure. But you have to be alive in the late 1970s to understand just how awful Jimmy Carter was. I have never seen the morale of the country as low as it was under Carter.