In 2016 52% of British voters chose to leave the European Union with no clear plan of what would happen next. The permanent damage to the UK economy was predictable and inevitable. Why did so many people vote against their own best interests? Because each had his or her own magical fantasy of good things to come, never mind all the bad stuff that could and did happen.
I turned off the 2024 Biden-Trump debate after 15 minutes because I couldn't listen any more. I assume that Democratic leaders whom I respected in the past know President Biden better than I do, and if they're worried then I'm worried, too. However I have not heard any credible plan from anyone to replace the President with another candidate likely to win the support of the majority of voters. "Let's convince the President to step aside and then we'll think about what to do next" is not a plan.