He was forced out by Democrats, he did not simply drop out on his own.
Do you really think that if Kamala Harris had gone before the news media, and said she refused to join with the other Dems to kick Biden to the curb, that Biden would have still been forced to quit? Biden was refusing to drop out of the election just a day or two earlier. They waited until after the primaries were over, so the people could no longer chose their candidate. Then they ganged up on Biden, threatened him, and stole the election from him.
And the mindless sheeple, who call themselves Democratic Party voters, simply went along with all of this.