There are degrees of evil.
In a hypothetical election between Hitler and George W. Bush, every thinking person would choose George W. Bush despite his terrible record on, say, the Iraq War.
Now on the issue of sexual assault, Donald Trump vs. Biden is the equivalent of Hitler vs. Bush.
Is it possible Biden sexually assaulted Reade? Yes, it's possible. Biden denied the allegations, but a denial only creates a "he-said, she-said" situation. It doesn't supply instant proof of the accused's innocence.
Now when it comes to Trump:
1. There are 20+ public accusers of Trump who allege various forms of sexual misconduct. https://www.pbs.org/newshour/politics/assault-allegations-donald-trump-recapped
2. He admitted on an audio tape to "grabbing women by the pussy" and (mistakenly) thinking they loved it. (Why do we know he was mistaken in that? See item #1, above).
3. He barged in on Miss America contestants when they were changing.
4. And most troublingly of all: the child rape allegations involving Epstein I posted above. There are other women who have alleged actual rape as adults including E. Jean Carroll who is currently pursuing a case. https://www.usatoday.com/story/news/nation/2020/09/18/amy-dorris-joins-women-accusing-trump-sexual-assault-and-matters/5827868002/
Some of the above is undeniable (either because admitted by Trump himself or caught on tape), and some of it has yet to be proven definitively.
The various excuses offered by Trump's defenders -- they're all out for money, they're confused, Trump must have had their consent, etc. etc. -- just can't hold water when there are this many accusers.
Harvey Weinstein had 100+ public accusers spanning decades before he was finally convicted (just this year) on 3 counts of sexual assault. Just 3. It takes time for the wheels of justice to turn in sexual assault cases. That goes double when the accused person is the literal head-of-state and can't be criminally indicted while in office per OLC guidance.
But when it comes to these things: where there's smoke, there's fire.