If democracy is truly at risk, then why go with an adoption like Biden as candidate?
Either Democracy is not truly on the ballot or they(his handlers) believe their work positions are more important than the loss of democracy in
the United States.
Because it's nowhere near as simple as you (and many others) are making it out to be. If Biden dropped out now, Trump would most likely win.
First of all, they would need to replace Biden: with whom? No Democrat in the USA has anything close to the name recognition as Biden (except for Obama, who cannot be president again constitutionally).
Next, the whole party would have to agree on the replacement. In these elections everybody focuses on the 5% of voters who might actually change their mind in the next four months and swing the election. But Biden already has the first 45%--but would some other new candidate?
And while Biden has his issues, Republicans would rev up their media to come after the new candidate--as would Putin and Xi--and hence all kinds of new "revelations" would come to light about the new candidate just like they have for Biden (viz. all of the "Hunter Biden" baloney).
If Biden himself and the people around him were truly thinking 100% exclusively about the good of the country, I don't think they would have an easy decision to make at all.