When you looked at the 538 forecast, the most likely outcome in their simulator was precisely the one that occurred.

At some points, Polymarket had a higher probability for Kamala too.

Nonsense. Trump led in every swing state prior to election in aggregate poll analysis. Each swing state may have had an outlier Harris poll, but to say no polls existed with Trump leading is definitely incorrect. There were no surprise state outcomes at all in 2024, and the election was effectively over by 9pm Eastern time. Maybe you mean some kind of popular vote poll nationally, but that isnt how the US votes and also doesnt represent 'all polls'. I checked RCP archives and they show 7 polls for Harris leading nationally, and 10 polls for Harris losing nationally.

And let us not forget Harris was only even a candidate for 3 months. How Harris even makes it into the training window without Trump '24 result is already amazingly unlikely.