I'm fairly certain Trump will win the electoral college; the popular vote could go either way, but he's in with a string chance there too.
His supporters are rabid and there really is nothing he could do to make them not vote for him - and there are lots of them. They are also much more likely to make the effort to go and vote, and help others go and vote (drive elderly relatives there, that sort of thing) because of their belief in him. Then there are those who vote republican come what may, and those who don't like Trump but like Pence (not many, but there are some religious types who do) and conspiraloons who don't actually like a lot of Trump's policies, but have bought into the various Qanon type theories.
It doesn't really matter that the economy's fucked, the virus isn't under control in any meaningful way, or anything you might expect people to give as a logical reason for not voting Trump. A lot of the time people don't actually vote for logical reasons - hence working class people voting for parties that hate them.
On the democrat side, Biden's support is a lot weaker. I mean, it's reasonably good in a normal year, but he doesn't have as many of the same insanely worshipful fans. And some people believe he's a paedophile sex offender - but, weirdly, don't generally seem to care that Trump definitely is a sex offender. Then there are those who hate Kamala Harris, for being a woman or black or Asian. Women don't necessarily vote preferentially for women. Plus some people believe Biden "stole" the nomination from Sanders.
There'll be a lot of people who hate Trump but also like Biden, so will vote for a third candidate, like they did last time.
So Trump's vote won't be split, but Biden's will. I wouldn't be surprised if he increased his vote share.
People seem to have forgotten what the Dubya presidency was like. Loads of people were predicting he didn't have a hope of a second term, but he won reasonably securely.