Now, let me ask you this, do these statistics imply a catastrophe? In my opinion, definitely not.
If anything, the statistics support anywhere from a substantial improvement (black and Hispanic voters much prefer Kamala to Joe) to a very slight decline (as you pointed out, a 2% greater gap between 18-34 voters). I am not sure why there is such a strong reaction though. The numbers you yourself selected do not indicate Kamala being substantially less popular than Biden. In fact, in my opinion, they show her as more popular than him.
Just for due diligence’s sake, I did some additional research. Here are some quotes I pulled:
View attachment 650915
While this is definitely not a fantastic statistic, it shows that Kamala Harris is much more likely to hang onto Gen Z/millennial voters than either Joe Biden or Donald Trump when alternative candidates are introduced to the race.
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I found more evidence that Harris eclipses Biden in terms of young voter popularity, this one is from polling done by the New York Times. It is a little narrow because it only focuses on Pennsylvania and Virginia though.
The point I am trying to make here is not that Harris is not more popular than Biden with younger voters. I personally think she is, but the evidence I found to support that belief is marginal. You can believe that she is slightly worse if you would like. The point I am trying to make is this:
she is definitely not catastrophically worse than Biden. I think believing that she is way worse than him with any key demographics is disingenuous to or misinterpreting the facts.
I think you might be scared of the fact that bad orange man wins because this political move seems disjointed and brazen to you due to a lack of historical precedent, and the fact that Joe Biden’s presidency was very uncontroversial. You want to avoid a worst case scenario, and you genuinely believe that Kamala is not as well-equipped to defeat evil as Joe is, which is fine. I think what might help you most would be to place a trust in Kamala to get it done. She has a lot of pros that Biden cannot share, and a lot of pros that he does share too. I am sorry to say this: I don’t believe you know better than the people who strategize campaigns for a living. Having faith in this to all work out instead of feeling doomed will probably soothe your soul too, so there is benefit in that regard as well. And if you want to double down and disagree with me on all of this, I won’t stop you either. I just hope you do it for your own sake too.
Kamalomomola

FTW!