Here's the thing: They did not have legitimate concerns about the economy, immigration, or crime. They had lies, lies and more lies that they had been fed for years, tailor made by Republicans to prey on their fears, and they convinced themselves that those lies made their "concerns" legitimate. So yes, they were very much unfounded. Crime was down nation wide, immigration is 1000% not the horror show republicans have been fearmongering about, and given that we'd just come out of a global upheaval due to an international pandemic, the economy was doing pretty fucking well. Inflation was under control, things were in general starting to come back to normalcy, and almost every major problem people were legitimately "concerned" about were things that the President has very little direct control over (like the price of eggs), so yes, Biden and his administration were actually handling shit just fine, for the most part.
But the vast majority of the American electorate are easily manipulated knee jerk reactionaries completely unable to see beyond their own noses, so they voted to literally skullfuck democracy because a known pathological liar told them what they wanted to hear.
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Yeah, not even close.
For one, Hillary wouldn't have been stupid enough to shitcan the only people keeping tabs on the Chinese, so there would have been significantly more likelyhood of a much earlier warning being sounded.
For two, The Obama administration LITERALLY left Trump a wargamed scenario playbook for handling an nation wide pandemic when they left office, as well as a group of trained professionals who's job was to make sure the country was prepared for a pandemic. Trump took that entire thing and junked it. Hillary would have had it available and ready to act on.
The Trump administration catastrophically mismanaged the pandemic because he did stupid shit like give important duties to people completely unqualified to handle them, or his constant undercutting of the actual experts in the room. None of that shit would likely have happened under a different administration.
Literally any other administration would have handled the pandemic orders of magnitude better than the Orange Dumpster Fire's administration did.