Is this even wrong? I think if Kamala had been a white guy, she would've done a lot better and the Democrats might very well have rallied behind her instead of Biden. Yeah, she sucks ass, but she's not particularly worse than any of the other Dems. The only reason she's the candidate now is because she happened to be VP while Biden basically died during a live debate.
The only people who support a primary challenger are people who hate the incumbent. You just don't primary an incumbent. Her chances were irrelevant so long as Biden was in the race.