she's not going to enter a suicide bid against Harris
There is not such thing as a "suicide bid" against Harris. She got fewer votes than Joe Sestak in 2020 and would be a heavy underdog for the nomination.
She also would be the sitting Vice President in 2024, and thus would be heavy favorite against almost any challenger by default (when was the last time a Vice President who ran for their parties nomination, lost said nomination?)
No Vice President who was as unpopular as Harris is has ever even run for the nomination, so you're suffering from an extreme selection bias. A majority of the sitting Vice Presidents nominated had previously been credible presidential contenders in their own right; none had mounted an embarrassing fringe run like Harris's. If, e.g., Cheney had run in 2008, he would have been washed out of the primary.
She was picked for the job specifically because she
isn't a credible successor and therefore preempts any efforts to get Biden to resign or forego a 2024 run due to his age. Nevertheless, she has a chance in 2024 or 2028 if she is the unpopular sitting
President (see Ford and Carter), which is why she took the offer.
