Lol.
Harris was the obvious alternate candidate under these circumstances for many reasons. The lack of other quality options in the primaries is why the Democrats were left with Biden, and gave them no other choice than Harris with less than four months left.
The Trump campaign is right to be scared - she'll do better than Biden would have, and will bring people who didn't want to vote for geriatric white men into the voting equation.
But given Biden's f**k-up in hanging on for a second term for way too long, Harris will be doing good if she can stop the Republicans winning control of Senate/Congress, even if Trump prevails to the White House.