The story on how he wasn't taking calls from Biden/Harris was starting to pick up steam. If this next Hurricane is as bad as it looks, I think he realized it would damage his career more than Harris's.
Three things about the betting markets:
1. As with any binary prediction on the election, it can't be wrong. If Trump has a 1% chance of winning, and he does, then that 1% paid off.
2. It's basically the median opinion of the public. If I trusted the public's median opinion, then I wouldn't have to worry about this election. Roughly half the voting public thinks Donald Trump was a competent President. It boggles the fucking mind how stupid we are. The gambling sites are pulling from the same absurd think tank. What kind of odds can I get that in the next year, it will be announced that we have diplomatic relations with several alien species?
3. Even the people that bet on those markets believe they are wrongs on the odds. There would be no reason to bet otherwise.